Re: [Tutor] Firefox Bookmarks
Are there any modules I should know about? Specifically How can I read/write from places.sqlite? Hi, pysqlite3 is the python wrapper for the SQLite libs. It is included with Python 2.5 and newer. Docs are at http://oss.itsystementwicklung.de/download/pysqlite/doc/usage-guide.html Have fun Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] os.path.exists(path) returns false when the path actually exists!
Iyer wrote: Adam wrote: From the library documentation: Return True if path refers to an existing path. Returns False for broken symbolic links. On some platforms, this function may return False if permission is not granted to execute os.stat() on the requested file, even if the path physically exists. So the better question is, does is this file a broken symbolic link or can os.stat() be executed on it? How do I find if it is a broken symbolic link in Windows 2000 ? os.stat(path) returns an OSError saying that there is no such file or directory Just to check, try to do away with the backslashes. Windows will accept a path with forward slashes just as well: os.path.exists(c:/winnt/file_name) Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Python Browser based?
Hi, Do you want to: 1) use Python from a website or server without installing it in a computer? 2) use Python to do things with the Internet or servers, website, etc? Hugo [EMAIL PROTECTED] wrote: How can I used python online. I'm getting my hoster to install python and I'm wondering how Do I use python online? ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tuto ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] File storage vs DB storage.
Hi, Managaing a lot of files is not a nightmare if you use/build the right tools. Why not saving filenames in the DB and then just using the ordinary web server to deliver them? Getting the blob out of the DB and then serving it through the web app is going to be a lot slower than letting, say, Apache do it. I wrote a system that kept 15000 files in a directory tree. You just let your software deal with them Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Movies from jpg files
János Juhász wrote: Thanks your response. It should works well with some images, but I would do it with a scheduled way with some 1000 files. Hi, I previously have used python to control mencoder. Mencoder does the combining and putting together into a video. You script the arguments and the command line switches to mencoder. Maybe use the subprocess module? or the commands module for very simple tasks? http://www.mplayerhq.hu/ http://en.wikipedia.org/wiki/MEncoder Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] how to run a text file in an interpreter?
Hi Tonu, Tonu Mikk wrote: I do not know what the author means by running a text file with the interpreter. I noticed that I came across an obstacle early on in trying out the code. What plattform are you in? Linux, Windows, Mac? Check out the faqs at: http://www.python.org/doc/faq/windows/#how-do-i-run-a-python-program-under-windows ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Quicktime Python
Miguel Oliveira, Jr. wrote: Hello, Just wondering: is there a way to play quicktime .mov files from python? I am trying to run an experiment and would like to have Python to play the .mov files I have in a given sequence (or in random), in full screen and to record a log of the files that were played, the order and the time. Any help will be very much appreciated. I would use mplayer. You can control mplayer through a simple text interface called slave mode and log what you send to it. I've got some code you could use, using the subprocess module if you want it. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] IOError: decoder jpeg not available
Hi, It looks like there is a capability you don't have installed in your image processing lib. but you really give us nothing. Please tell us: - Was this working before in any other operating system or python version? - What module are you using for working with jpeg? - Show us the code that throws this exception, or how you use it.. And maybe we'll have some info to help you out. Tsila Hassine wrote: Dear fellow Pythoneers, I have recently upgraded to Mac 10.4, and since then this error appears when trying to manipulate an image (resize it actually), can anyone help me out ? ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] howto call DOM with python
I too wish it worked. In javascript, it works because the browser has a Javascript implementation. There's no stock browser with a Python implementation, and I've looked for any client side implementation with no success. Hugo Ismael Farfán Estrada wrote: hi there I was wondering wheter someone knows how to use python to write a client-side scripts like if it were java, I want to get someting like this working html script type=text/python window.alert(python) /script /html but nothing happens. I don't know javascript but this code works if I put javascript instead of python, I've also tried with pythonscript python-source, etc hope you can help me, I'm using GNU/Suse, Opera, and Firefox for test _ El mejor destino, con los mejores contenidos http://www.prodigy.msn.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Running an exe from Python
Hi, Take a lok=ok at the module named subprocess. You can catch the output of invoked programs with this. There is also a module called commands but it its not available in windows. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Python code to connect using PPPoE
Hi Johan, PPPoE is both in the Linux Kernel (for the low level work) and as some executables and scripts. It fou want to establish a connection from a Python script (E.G. ehn the computer has no internet access and you need it) The best way would be to call the appropriate utilities, and parse their output. This means calling adsl-connect, ficonfig, and the like, maybe parsing the output from ifconfig. Take a look at the module named subprocess to do that. Reimplementing these utilities in Python is some work, but doable. Implementing PPPoE in Python, reading the device files and all that... well... it's almost nonsense. For this, you have to use the kernel. Johan Geldenhuys wrote: Kent, I want to establish the connection with Python. I think in Linux you can use a PPPoE package to make life easier, but I don't want to use the Kernel to do that. Johan ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Cause-Effect, Isikawa, fishbone diagram
Hi János, Reportlab is a very complete PDF library, but it is not very simple, and does not have shortcuts for what you need to do. You'd have to come up with the code to get a fishbone diagram from the textfile. But it does help you with the PDF. There are some graphing packages, but they're most for scientific graphs. Like http://matplotlib.sourceforge.net/ Hope that helps, Hugo János Juhász wrote: Dear All, does someone know any python based solution to draw a cause-effect diagram into PDF from a simple textfile ? It is also called a Fishbone Diagram, because of its shape, or an Ishikawa Chart, after its originator, Kaoru Ishikawa I feel, it can be converted from a structure like this. Title Effect Cause1 Secundary Tertiary Tertiary Cause2 Secundary Tertiary Cause3 Secundary Tertiary It is probably a simple function. Yours sincerely, __ Janos Juhasz ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Perfect Python web stack?
Hi, Check the thread in the archive. This has been discussed recently. I have been exploring Django, and since I don't want to go into SQL now, I like it. It generates DB code from your model and you don't have to do SQL. It helps to do your app FAST! But that's just my opinion. Hugo OkaMthembo wrote: Please help me to decide. I might have asked some of you before, so please bear with me. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] python web dev
OkaMthembo wrote: this is my first post. please could you tell me which is the best lightweight python web framework? also, which is the best templating language for python? (which can handle other data formats in addition to text). so far im lured by Cheetah, although i havent done any web dev with python yet. If you really want to go light, you may want to try Albatross, as others like Django are pretty heavy. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] problems pickling functions
Arild B. Næss wrote: I haven't found out how to change the working directory in IDLE, though – and for some reason it seems to be a different one this session from the last one. Does anyone know? (I use a mac by the way.) take a look at os.chdir() This changes the interpreter's working dir (and thus whatever you're writing into the prompt in IDLE) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] XML-RPC data transfers.
Luke Paireepinart wrote: But the main strategy is to get the data out of the ImageGrab object. one way is stated above - use the save method to write to a file. another possible way is to create a filelike class, implementing 'tell' 'seek' and 'write' methods, that just collects all the data written to it and keeps it in memory rather than writing it out to a file. This is hinted at in the documentation for im.save(): You can use a file object instead of a filename. In this case, you must always specify the format. The file object must implement the *seek*, *tell*, and *write* methods, and be opened in binary mode. (I assume it means you can use a file-like object, also, but it's possible that you can't, and I leave it to you to test that :) ) hmmm StringIO module maybe? Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Python and rpy
Geoframer wrote: However i switched to Ubuntu 6.10 today (from WinXP) and to my suprise it does work under linux! :-) Probably Numeric is included in Ubuntu's Python distro. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] is gotchas?
Hmmm! Hmmm! Lookee here: ## console session a=[1,2] b=[1,2] a is b False c='1' ## one byte d='1' ## one byte c is d True c='1,2' d='1,2' c is d False The Hmmm! is emmitted because I'm thinking that if everything is an object in python, then why does `c is d` evaluate to True when the assigned value is 1 byte and evaluate to False when the assigned value is more that 1 byte? One and two byte strings are currently optimized in cPython as the same object, referenced multiple times. Note that this is not to be relied upon! Jython, Ironpython, Python3000 or cPython itself may break it! Still cannot find a reference doc for this Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How to read content in a tar file with tarfile module
Magnus Wirström wrote: I have written a app that makes a tar file and all works well... Now i want to expand that app so it can read read the tar and give me the contents of the tar file. How is the best way to do this ? I can't find a listdir like function in tarfile. Can anyone point me in the right direction? Hi, is this what you're looking for?? (tarfile Object docs) getmembers( ) Return the members of the archive as a list of TarInfo objects. The list has the same order as the members in the archive. getnames( ) Return the members as a list of their names. It has the same order as the list returned by getmembers(). Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] question about looping.
Doug Potter wrote:
for i in routers:
os.system('/bin/touch' %s) % i
of course this dosn't work.
Is there a simple way to get this done?
Yep, someone already answered that you can create the file in write mode
and then close it, but I wanted to add a little more in why your
solution doesn't work.
You're not interpolating the filename INTO the os.system string
The following would work
for i in routers:
os.system('/bin/touch %s'%1)
Granted, you should also provide a filename with a full path for simplicity.
HTH
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] revisiting struct and bytes again.
i can make a byte a string or number or whatever now. Up to the number 255. I now have a problem with something that comes in as a 4 byte representation of the number of seconds since 1970. Hi Shawn, That's an epoch time as used in UNIX. Are you sure that what you're trying to do cannot be done with the Python time module? What is it exactly that you're trying to do? Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] omnicomplete vim python
anil maran wrote: do u guys know how to enable omnicomplete using vim for python thanks Google is your friend, here's a page: http://www.vim.org/tips/tip.php?tip_id=1311 Actually, I didn't ven know this existed. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] python
Hi David, Have you read the grat explanation in Alan's tutorial? What problem specifically are you having with functions? http://www.freenetpages.co.uk/hp/alan.gauld/ Get back to us with any questions... David Wilson wrote: can you explain functions in python to me and give me some examples ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Is there a method like this already?
Nathan Pinno wrote: Is there a method in Python like this already: [code] #This program calculates how many days it has been from one day to the other. Hi, Check the datetime module, it will give you distance between dates in the units you specify. It is included in the standard distribution. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OT: any good newsgroup or other forum for MP3 internals discussions?
Terry Carroll wrote: I apologize for this off-topic question -- the only real connection to Python is that I'm using Python as my programming language. I'm writing a program to analyze an MP3 file's contents. I need to find a newsgroup or other forum to ask some questions about file format internals. Nothing's jumping out at me, looking through the list of usenet newsgroups. I've found dozens of sites with relevant specifications, but am looking at one or two rogue files where either I'm misunderstanding the specs, or the file is nonconformant (but some MP3 programs can read them, so I'm betting it's me). Are you using any kind of prefabricated Python module for this? Maybe their implementation of MP3 tagging is enlightening to you. Remember that ID3 in MP3 was a dirty hack at the beginning, so it is likely that may files are nonconformant or that many different programs simply follow their gut, as there was no specification. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sockets
Matt Richardson wrote: I need to send some data, 2 strings and a list, to a remote computer. After thinking about it some last night, it wouldn't be hard to just send it all as a string and then parse it on the receiving end. Well if the excercise itself is not parsing a string, you can just use pickle to serialize your objects. Look up the documentation for the pickle module. You can transform many objects into byte streams and then send them over the network. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Halting execution
It would be similar to Perl's die() commmand. But no, in Python the argument is the error status of your script. You'd have to do something like def exitnow(arg): print arg #maybe sys has not been imported import sys sys.exit(1) Hugo Ertl, John wrote: Matthew, Not sure if ipython is different but have you tried sys.exit(stoping now) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] question about run time
I have made scripts that work on many files (sometimes just some tens) and appears that filesystem structure caching in Linux is very efficient. That's why it runs very fast later. I've seen this in Slackware, Debian, and RH, so I guess it's just a linux/FS/disk thing. Try doing 'find' combined with md5sum or something disk-intensive, but unrelated with python to see if it exhibits the same problem. Hugo Ertl, John wrote: I have been using python for sometime...and occasionally I noticed significant delay before the code would run but unitl now I have been able to write it off to other things. Now I have a short script that I wrote to check some files and print out a few lines. I have noticed that usually the first time I fire it up in the morning or after a long time of not running it, it takes 10-15 seconds to run and the output to the screen is very slow...maybe 1 second per line. If I run it soon after that it runs and the output is on the screen in less then a second. I would think this has to do with compiling but I am not sure. Any ideas how to speed this up? I am running python 2.4 on a RHE3.0 cluster. Thanks, John Ertl ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How Big Is Too Big?
Just wondering how many lines of code is the maximum to post in the list to have it critiqued. I realise people are using their own time to help others in here for no real personal gain and I would hate to impose on their goodwill. Would about 100 lines of code be considered too much? My 2 cents: Length is really no problem, the problem would be: 1) inconvenience of too long an email. Post a link to a webpage with the code if it is longer than, say, 100 lines. 2) It is much more important for me that the poster seems to be really working on the issue, and willing to learn. Then I'd have a look at code any size :) But this is just my own opinion. Greetings, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] cycle w/ shuffle
Hi Kevin,
kevin parks wrote:
I am trying to write a loop that iterates over a sequence and do
something x number of times. But sometimes i will need more events
(larger number x) than i have have items in the sequence, so if i need
more events that i have stuff in my sequence i would like to have the
loop reload and shuffle the deck and start all over again, reloading as
many times as necessary to get the number of events needed. I suppose i
could go around cyclically modulo the list size but i would want to
shuffle the deck before doing that again...
Why not save the iterable it in the generator, then just reuse it? You
can copy the iterable like this:
import random
def cycle(iterable):
saved = list(iterable)
#notice how I saved into a list, for I could not shuffle a TUPLE!
while True:
for element in saved:
yield element
random.shuffle(saved)
def test():
seq = ('one', 'two', 'three', 'four', 'five', 'six', 'seven',
'eight', 'nine', 'ten')
loop = cycle(seq)
count = 1
for item in range(25):
print count, loop.next()
count = count + 1
#you could use enumerate() instead of manually making the loop here.
#for i, v in enumerate(loop):
#print i, v
Hope that helps,
Hugo
if __name__ == '__main__':
test()
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Avoiding the use of files to store intermediate results
Remember duck typing. An object just needs to look like a file in order to be used like one. Guido's time machine has already forseen your problem. Take a look at the StringIO module. It allows you to use a string where you would normally pass a file object. Hope that helps, Hugo ## While this works, I find it messy, as it creates some intermediate files. I was wondering if there was a better way to do things all in memory, in an OS independent way. [Note that the complete application is approximately 665 lines long ... a bit too much to post all here :-)] André ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] GUI
Ok, If I can get it for free, I might as well go with say wxPython. Thanks Yes, free as in beer, as in speech, and cross platform. Oh, and better documented. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Raw Bits! (Control characters ahoy!)
doug shawhan wrote:
I am in the middle of a project that requires me to send and retrieve
information from a machine connected to a serial port. My problems are
these:
1. I cannot send control characters
2. I cannot read data streaming from the serial port
I have been doing fine with:
os.system(echo '5' /dev/tty00)
os.system(echo '8' /dev/tty00)
Hi Doug,
Echo just opens the file and writes to it, closing it afterwards. if you
have used setserial correctly on the portt, then the equivalent Python
commands should work.
Note that the echo command adds a carriage return at the end.
Reading from the serial port has also been problematic. I find that
simply opening the port /dev/tty00 file and using readlines(), read() or
whatever gives me empty strings or lists. Pbth.
If you use blocking, then reading should not give you anything empty,
but data, no matter how long it has to wait.
So first: how should I go about adding the hex escape sequences (\x0a
and \x50) to the above strings in their raw form?
fileo = open('/dev/ttyS0', 'w')
fileo.write('5' + '\x0a\x50')
#\x0a is a linefeed (do you want to do that?)
fileo.close()
You may use fileo.flush() instead of close, for avoiding buffering and
not having to close the file.
second: what method should I use to read a raw stream from the serial
port for a given period?
fileo = open('/dev/ttyS0') #read only
data = fileo.read(1) #just one char
fileo.close()
#This waits forever. For a given period, use the select module (UN*X only)
import select
select([fileo.fileno()],[],[], 1.0)
#This will wait for 1 second for output from the file. Then the return
value will tell you if the filehandles have data. ([], [], []) means no
data to read.
I have looked carefully at the neat and tidy miniterm.py example in the
pyserial examples directory, and see how one can continuously read via a
thread from the port, but have not been able to replicate it thus far.
I never use threads for that, I always use select(). Then again, I'm a
unixhead.
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] encoding
kakada wrote:
LookupError: unknown encoding: ANSI
so what is the correct way to do it?
stringinput.encode('latin_1')
works for me.
Do a Google search for Python encodings, and you will find what the
right names for the encodings are.
http://docs.python.org/lib/standard-encodings.html
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dictionary datatype
kakada wrote: I assign: n = 0x2018 print dict1[n] Then: KeyError: '0x2018' Notice the error menstions a *string*. You probably mistyped it, not in the email, but in your actual program. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Tuple (Section 9.3)
Hi Kaushal, I might have to do a little guessing and see what is not clear from the explanation. The whole point of returning a tuple as opposed to, say, returning a list, is the fact that tuples are NON mutable. That is, *apparently* you would not be returning a reference, but the values themselves. There is no better example I can think of, than the one you already read. If you want a function tu return multiple parameters so that you can do. ret1, ret2 = func() then have func return a tuple. That's the whole point of the chapter you read. Maybe there is too much information in the discussion that does not look useful to you if you have not run into a problem where you need it. I hope this is not some kind of homework :) Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Python performance resources resouce usage hints
Liam Clarke wrote: Each thread's run() method basically looks like this - while True: try: data = self.queue.get(False) self.DAO.send_data(data) except Empty: if self.shutdown: print \DAO closing return continue Hi Liam, I checked the response by Kent. I completely agree with him in that the problem is the endless polling you have. However, you do not have to implement a sleep in your loop; the main issue may be that you are not using the facilities of the 'get' method in the queue. From the queue docs: get([block[, timeout]]) Remove and return an item from the queue. If optional args block is true and timeout is None (the default), block if necessary until an item is available. If timeout is a positive number, it blocks at most timeout seconds and raises the Empty exception if no item was available within that time. Otherwise (block is false), return an item if one is immediately available, else raise the Empty exception (timeout is ignored in that case). You are not using the optional timeout and blocking which 'get' provides (!) Try setting it and see your CPU usage go down. This will implement blocking, and the queue will be used as soon as data is there. Set block to True and a timeout if you need to use it (looks like you only need blocking) while True: try: data = self.queue.get(True) self.DAO.send_data(data) Hope that helps, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] function caller
josip wrote: Can someone explain me function and caller relationship when passing arguments? Hi... what do you mean? Is there something specific you're not getting if you take a look at: http://www.ibiblio.org/obp/thinkCSpy/chap03.htm http://docs.python.org/tut/node6.html#SECTION00660 We'd be glad to help with that, but we need the doubt to be more specific. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Quick question,
Carlos Benevides wrote: Hi, Can someone tell me what the r before the expression means, as in re.compile(r'(\.exe|\.zip|\.pif|\.scr|\.ps|\.pdf|\.ppt)$')? It is not specific to regular expressions, it is called a raw string. http://docs.python.org/tut/node5.html ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] preliminary app design question
Richard Querin wrote: My question before I start is whether or not using an XML format for the individual file formats is the way to go, and if I have to anticipate every little thing in the file formats before hand. I don't want to do this, I would rather like to be able to just add and modify things as I go with the least amount of hassle along the way. Any ideas on how to generally approach the file formats? To quote PJE in http://dirtsimple.org/2004/12/python-is-not-java.html (Python is not JAVA) --- XML is not the answer. It is not even the question. To paraphrase Jamie Zawinski on regular expressions, Some people, when confronted with a problem, think I know, I'll use XML. Now they have two problems. --- Now seriously. Are there file formats meant to be used and understood by other programs in principle (we know it is a nice feature, but is it necessary?)? If the answer is yes, then XML may be the solution. Looks like what you are trying to accomplish can be done wrapping functionality into modules, then adding them together (classes, functions, etc) using a GUI master program. Saving complex data structures to files in Python is easy. Let it be pickling or using a Python database, like Kirbybase or Gadfly. If you need to communicate this to other applications, you may use simple extensions like those in XML-RPC(still no XML design and/or parsing). As for anticipating every single thing in the file format, this depends on whether you need to have fancy things like backwards compatibility. I would guess some dynamic data structure that allows for extension (like a dictionary of attributes, where you can always add new attributes) will do. hope this rant helps a bit Hugo Any suggestions would be greatly appreciated. I have zero experience with XML at this point, and very modest experience with Python/wxPython, but necessity is the mother of invention and I can learn what I need to know I think. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Question about large numbers of arguments
Dana Robinson wrote: Have the functions take large numbers of parameters. or Create an options class to pass the options around. Pythonically, I heard the distinct scream of DICTIONAR in my head. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] defined()
Alan Gauld wrote: Which language(s) do you know that has such a feature? And why do you consider it so useful that you expect to find it in Python? I'm not the original poster, but being a perlhead before, I can say it exists in Perl. It is very often used too. I used to miss it at first, but normally I now do the right thing semantically. Counting on the variable being defined or not is simply another bit of information. Assigning a value for that case is much cleaner. It is not used for black magic in Perl, AFAIK. Just normal testing. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] get a character of an ascii-value
Hi, Python strings are binary strings as they can contain any value, including 0 (NULL) Depending on the encoding of the string, this may or may not be printable, and characters over ASCII 127 will mean different letters and symbols. Check the docs for strings and encodings: http://docs.python.org/lib/standard-encodings.html http://python.active-venture.com/api/stringObjects.html Hugo In a I just got the answer from Pujo. How about r is bigger than 127. How can i get the character? For example, r = 191. Thanks, Sophon ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Program for outputing the letter backward
Hoffmann wrote: while index = index_zero: letter=vehicle[index] print letter index -= 1 The problem is that I get no output here. Could I hear from you? Hi, remember that the condition for the while has to be true. When does index = index_zero stop being true??? Hope that gets you going, Hugo Ps: there are easier ways of doing this in Python, consider the for statement. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Python help
Why not post where you are stuck or what you are trying to understand? and we'll give you help and direction. What we cannot do is solve your homework for you. Hugo Natasha Menon wrote: hi, i need help on a terrible homework assignment. do ul offer hw help? ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] get a character of an ascii-value
Keo Sophon wrote:
Hi all,
I wonder how to get a character of an Ascii-value. For example, i have r =
37. So i wanna print the character of 37. Is there any function?
Hi ..yeah, it's called chr(), and its opposite is ord()
ord('r')
114
chr(114)
'r'
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] TypeError: dict objects are unhashable
Ben Vinger wrote:
But I get:
TypeError: dict objects are unhashable
Unfortunately, I just can't see what I'm doing wrong
InnerDict = {}
InnerDict[U] = P
accounts[InnerDict] = U
Your logic is not right somewhere around this. I do not have a lot of
context, nor the full error message, but what it says is that you
*cannot* use a dictionary as a key for a dictionary.
In this line:
accounts[InnerDict] = U
this is what you're doing.
You should be using a dictionary with the tuple, something like this:
InnerDict = {}
InnerDict[U] = P
accounts[(U, P])] = U
Again, I do not wuite get why you want to do it like that. If you could
explain a bit more to us
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Mysql BLOB strangeness?
However, there is still a learning point that might be missed here - how does Python grab BLOB data-types, and how do you manipulate them? If it were a file, would you just be able to grab the file without the array? The basic issue is: what form is used for representing arbitrary byte data of arbitrary length. 1) strings: strings in python are arbitrarily large and can store any byte values (compare this with other languages like C where the number 0 signals the end of a string) Strings are OK, and that's what the standard library writes to files. 2) arrays: there is but one problem with strings, and that they are inmutable: you have to create a new string everytime you want to change an old one. Long data chunks are inefficiently worked when using strings, so you may use arrays (array.array) which can be changed in place. Of course there are many more options, like a tuple or a list of 255 or less ints, but these are the main contenders for byte valued sequences. Hope that clears thing a bit, Hugo -- http://www.monkeez.org PGP key: 0x7111B833 ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Help with re.sub()
Hi John,
I would just like to suggest a different approach. Like the old saying goes:
Some people, when confronted with a problem, think “I know, I’ll
use regular expressions.” Now they have two problems.
— Jamie Zawinski, in comp.lang.emacs
If the delimiter is always the same ('@') you can use split() to get the
data. Then you can arrange the data in a dictionary of lists, like this.
collapsed_data = {}
for line in mydata:
id_part, data_part = line[:-1].split('@')
try:
collapsed_data[id_part].append(data_part)
except KeyError:
#first time insert for that key
collapsed_data[id_part] = [data_part]
for id, data in collapsed_data.iteritems():
print '@'.join([id] + data)
That should be it. Python's data types are very powerful. Of course you
could just build a huge list comprehension that does it...
Hope that helps,
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] scaling values
Hi Kevin, Do you mean:? 1)take the highest value in the list hval, take the lowest value in the list lval 2) pass top and bottom NEW values for the list: ntop nbot 3) then build another list where hval is replaced by ntop, lval is replaced by nbot, and everything else is geometrically scaled in bewteen? AFAIK, there is no such function in the standard lib (maybe someone knows better) but it is not hard to build such a function. Have you tried? It would be something like: def scaled(x, ntop, nbot) See that you can use min(L) and max(L) to get lval and hval Try it, and if you run into problems or have questions, don't hesitate to ask. Hope that helps, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] problems with numbers in my python code
Hi, However, I can't seem to get the program to treat the numbers as numbers. If I put them in the dictionary as 'THE' = int(0.965) the program returns 1.0 and if I put 'THE' = float(0.965) it returns 0.9655549 or something similar. Neither of these are right! I basically need to access each item in the string as a number, because for my last function I want to multiply them all together by each other. The latter is right. Floating point numbers have limited precision (limited by the number of bits used in the representation) The exact number .965 does not exist in the representation for your computer, but smart displaying can be done: .965 0.96497 print .965 0.965 var = .965 var 0.96497 print var 0.965 str(var) '0.965' repr(var) '0.96497' Take a look at apprendix B in the tutorial: Floating Point Arithmetic: Issues and Limitations http://docs.python.org/tut/node16.html Also the decimal module may be the solution to your problem: http://docs.python.org/tut/node13.html#SECTION001380 Hope this clarifies things a bit. Hugo I have tried two bits of code for this last bit, but neither are working (I'm not sure about the first one but the second one should work I think if I could figure out how to return the values as numbers): 1st code value = codons[x] * codons[x+1] x = (int) x = 0 print value x +=2 if (xr): new_value = value * codons[x] value = new_value x +=1 else: print new_value This gives the error message Traceback (most recent call last): File C:\Python24\code2, line 88, in -toplevel- value = codons[x] * codons[x+1] NameError: name 'x' is not defined Code 2 - the most likely code prod = 1 for item in (codons): prod *= item prod print prod Gives this error message: Traceback (most recent call last): File C:\Python24\code2, line 90, in -toplevel- for item in (codons): prod *= item TypeError: can't multiply sequence by non-int Can anyone help me solve this problem? Thanks. -- View this message in context: http://www.nabble.com/problems-with-numbers-in-my-python-code-t1259271.html#a3339964 Sent from the Python - tutor forum at Nabble.com. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] execute an OS command, get the output
Hi Terry, abc = executeit(commandline)or executeit(commandline, abc) Looks like you are looking for the commands module, it provides: getstatusoutput( cmd) getoutput( cmd) getstatus( file) Which do exactly what tou want. Take a look at the docs at: http://python.active-venture.com/lib/module-commands.html Hope that helps, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Are we the same?
I believe it is just spam pretending to be a legit invitation, that made it to the list. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving .csv file as an xl worksheet
Hello, .xls is a proprietary format used by Microsoft office, and unless you have the specs for that format and are willing to implement them (very very hard) it would not make much sense. If you absolutely need that, then maybe a macro in VBA from Excel itself may be a better option. Changing the file extension only (just the filename, not the contents of the file) can be done using the shutil module in Python (high level file manipulation) Hugo arun wrote: Hi , Can i save a file with a desired extension?? for ex: I have a .csv file (test.csv) and i want to save this file as test.xls from a python script. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Analysing genetic code (DNA) using python
Hi Anna,
Let's see one thing at a time.
wrote:
** If the three base pairs were UUU the value assigned to it (from the
codon value table) would be 0.296
This can be done in Python, and one appropriate tool may be a dictionary
such as:
dna_table = {
UUU : 0.296,
GGG : 0.3
}
print dna_table[UUU]
0.296
You'd use the table to look the corresponding value.
Of course, you'd have to so some programming to get your ASCII
translation tables converted to a dictionary.
The program has to read all the sequence three pairs at a time, then I
want to get all the values for each codon, multiply them together and
put them to the power of 1 / the length of the sequence in codons
(which is the length of the whole sequence divided by three).
Rational powers are supported by the pow() function in module math, see:
import math
math.pow(10,0.5)
3.1622776601683791
However, to make things even more complicated, the notebook sequences
are in lowercase and the codon value table is in uppercase, so the
sequences need to be converted into uppercase. Also, the Ts in the DNA
sequences need to be changed to Us (again to match the codon value
table). And finally, before the DNA sequences are read and analysed I
need to remove the first 50 codons (i.e. the first 150 letters) and the
last 20 codons (the last 60 letters) from the DNA sequence.
These problems are very straightforward in python with string methods,
take a looks at the docs at:
http://docs.python.org/lib/string-methods.html
I've also
been having problems ensuring the program reads ALL the sequence 3
letters at a time.
Line endings may be causing you problems if you try to read line by line.
Something like this should do:
#read 100 characters from your file
buff = fileo.read(100)
#eliminate line endings
buff = buff.replace(\n, )
#read three new characters
word = buff[0:4]
#consume part of the buffer
buff = buff[4:]
This is slow and can be polished. One approach could be reading
characters into a list and then consuming that list (strings are a bit
harder since you cannot change them) Also, the last expressions will
throw an exception when the list is too short, and you'll have to read
another chunk from the file.
Hope this all helps, please let us know how far have you got and when
you get stuck so we can help.
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Finding items in a list
As others have said, a concrete example would be great. For the time being, sounds like maybe regular expressions could do it. We don't know if your data is already in a list of small strings, or if it is just a huge string. Take a look here for an intro to RE, though: http://www.amk.ca/python/howto/regex/ Try to send a bit more specifics, we'll be here... Hugo Emily Patek wrote: Hi - I am trying to break apart a list into several smaller lists based on repeating nearly identical entries. For example, every so often there is the word CLUSTER with a number after it, like CLUSTER 1. I can find them one by one, but would like to do a while loop for while item in list = CLUSTER X. Is there a key that I can put in that means any text that comes after that would go from cluster to cluster without my typing in each cluster and number? I am a very beginner programmer and am trying to parse a file of gene-related information that is in a not-so-easy format. I put it into a list based on lines through the splitlines() method. I also thought about splitting the text by CLUSTER and then making each item of the list into a string that I could then split, but couldn't get that to work either... Thanks! Emily ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Tkinter, Frame and Canvas question.
Alas, there is some strange anomaly: it only does so (i. e. doesn't display that gray bar between the canvases) when run from IDLE or by double-clicking the renamed file test.pyw or run from the command window with the command: python test.py. Double-clicking test.py performs differently(!) and still shows the border between the two canvases. Who understands? (Or do you think my python installation is in a corrupted state?) No, it does the same on my 2.3 installation in windows. I will test on Linux. Actually, it displays the grey border, but if you scroll any window in front of it, everything except those borders are redrawn... (!) I'll check what it does on Linux and then report back... Thanks, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Bug in python
Hi, just a recommendation: try not to assume a bug beforehand, that's a quick way to get flames or just get plain ignored, especially in a list for beginners. The * is being given equal priority to %. Why isn't % given higher priority than *? Why should it? Doesn't it make sense that as '/' and * have the same precedence, '%' should have the same? Check the precedence for python operators here: http://www.byteofpython.info/read/operator-precedence.html http://docs.python.org/ref/summary.html Check the precedence for C operators here: http://publications.gbdirect.co.uk/c_book/chapter2/expressions_and_arithmetic.html So everything alright, also, left to right, as expected. Also, why am I getting a syntax error in the following? To get more informative messages, save all those statements to a file, and then try and run the file. It is extremely easy to mess up indentantion and make mistakes in the interactive prompt. Aslo you'll be getting information about the line number and such. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] pdf syntax
Hi, Syntax for composing a PDF is ugly PostScript. However, there are a couple of ways to use Python libraries to avoid the details. You can draw a canvas in Tkinter and then print it, then use something linke ps2pdf to do the conversion. http://effbot.org/tkinterbook/canvas.htm You can use ReportLab, which is intended specifically for generating PDF. Docs are very complete: http://www.reportlab.org/ The best language is of course Python, as this is the Python Tutors list ;) Hope that gets you started, Hugo saurabh akshekar wrote: Hi all my name is saurabh i want create n manipulate pdf files. can anybody tell me what is pdf syntax n how it works? also best or efficient language in which i should write program please reply ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] using popen(n) to intercept stdout
Hi Tim, You are correctly using the filehandles you have, but the man command must be sending the response into STDERR instead of STDOUT. This makes sense, since it is an error message. Take a look at popen4() and popen3() which both let you catch the standard error of a process. Also, in more recent versions of Python, take a look at the module named Subprocess. Hope that helps, Hugo Question: How do I intercept the first response? I.E. How do I get No manual entry for nothere into a variable? The object is to call another process on the same machine and capture the output of that process, assuming that the child process is writing to stdout. thanks tim ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] using popen(n) to intercept stdout
I also noticed that if you want to get the manpage, you will be hurt by the interactivity of 'man' (it uses less for paging) One way to get the whole manpage as text without paging is to do: man -P /bin/cat So you won't have to do strange stuff in stdin to get it to give you the whole text. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] using popen(n) to intercept stdout
Hi Tim,
Yes, you're on the right track.
a,b,c = os.popen3('wt *.py','r')
res = a.read()
The error you're getting has nothing to do with the result of the
command, but check, from the docs:
popen3( cmd[, mode[, bufsize]])
Executes cmd as a sub-process. Returns the file objects (child_stdin,
child_stdout, child_stderr). Availability: Unix, Windows. New in version
2.0.
Traceback (most recent call last):
File stdin, line 1, in ?
IOError: [Errno 9] Bad file descriptor
The 'a' variable is supposed to be the process' STDIN, you are supposed
to write to it. So if you want to read, it is the wrong file object, and
it is in write mode, therefore the IOError.
Also check that the above docs are for os.popen(), popen2.popen()
returns filehandles in a different order.
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Tkinter, widgets not displaying...
Hi Kent and John, Thanks a lot for the advice on how to improve my program. I will look into separating the data and model as John suggests here. I didn't know about after_idle() and after(); seems that dir()'ing the classes sometimes gives out a lot more information than you can chew at any given time :) Thanks, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] cgi script: how to continue a process in the background and return from cgi script
So, could some give me a pointer to possible solutions ? Do I have to make the last part of my program a seperate program and go through a system call ? Hi, I have had this problem before. The timeout problem with Apache remains because STDOUT of both child and the parent are open. Apache keeps thinking the CGI is still sending data until the filehandle is closed. I have solved it in the pas using this recipe, which is similar to the one you used before: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/278731 Hope that helps, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Tkinter, widgets not displaying...
Hi All,
I wrote a small turn delivering graphical app that is supposed to
display turns in a queue.
If I instantiate the class and call its methods, thus displaying strings
in several canvases, from the interactive prompt, everything works fine.
If I do it when running the script as a programs, nothing gets displayed.
If I call mainloop() at the end of my program, everything gets
displayed, but then I cannot use my own function classes. This program
will never respond to events, but just get called from a queue manager
script for display...
Here's the code:
#!/usr/bin/env python
from __future__ import division
import Tkinter
import tkFont
from Tkconstants import *
from time import sleep
class TurnQueue(Tkinter.Frame):
def __init__(self, master=None, pw=60, ph=60, panels=4):
self.ph = ph
self.pw = pw
self.panels = panels
Tkinter.Frame.__init__(self, master)
self.createWidgets()
self.pack()
def createWidgets(self):
Create four canvases and a warning window.
self.canvases = [Tkinter.Canvas(height=self.ph, width=self.pw,
borderwidth=1, background = '#FF') for i in range(self.panels)]
self.textbox_ids = []
# display them all, initialized
for i in self.canvases:
id = i.create_text(self.pw//2, self.ph//2, text='',
font=('bitstream charter', self.ph, 'bold'), fill='red')
self.textbox_ids.append(id)
i.pack()
def write_panel(self, panel_no, newtext):
writepanel(self, panel, newtext)
Set panel panel to text newtext
self.canvases[panel_no].itemconfigure(self.textbox_ids[panel_no],
text=newtext)
def read_panel(self, panel_no):
textcontents - read_panel(self, panel_no)
Read panel text contents
return(self.canvases[panel_no].itemcget(self.textbox_ids[panel_no], 'text'))
def insert(self, turn_string):
Insert a new turn into the queue, move the rest upwards,
delete oldest.
current_values = [self.read_panel(i) for i in
range(len(self.canvases))]
next_values = current_values[:]
next_values[:-1] = current_values[1:]
next_values[-1] = turn_string
# update all panel values
for i in range(len(self.canvases)):
self.write_panel(i, next_values[i])
if __name__ == __main__:
myturns = TurnQueue(pw=200, ph=100, panels=4)
for i in range(100):
myturns.insert(str(i))
sleep(0.2)
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] IDE - Editors - Python
I'm programming under Windows and I haven't found anything better than Stani's Python Editor (spe). It should be cross-platform. I second SPE under Windows, though under linux I keep using vim. The included utilities are great (I love Kiki) The only caveat would be that running wxpython programs could get you into trouble, as SPE itself is written in wxPython. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Tkinter, widgets not displaying...
Sorry for replying to myself, but I found a page that says that it can be done without threads... so it hit me: use threads!!! (duh) Ok, for future reference, this is the part where I use the classes I defined: if __name__ == __main__: top = Tkinter.Tk() myturns = TurnQueue(top, pw=200, ph=100, panels=4) #importing here is ugly, but just for testing. from thread import start_new_thread start_new_thread(Tkinter.Tk.mainloop, (top,)) for i in range(10): myturns.insert(str(i)) sleep(0.2) So now I see my line of canvases displaying numbers going upwards.. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] mapping problem
What about choosing a native Python data structure for this?
A list of attributes comes to mind, as presence of one can be easily
tested with
if x in attributes:
do_something
Here's a test:
elements= {}
elements['boat'] = ['a', 'b', 'j', 'k']
'a' in elements['boat']
True
Then it is just a matter of getting the fiels into the structure, and
then recursing through the elements, like this.
elements = {}
for line in table_fileo:
fields = line.split()
#get rid of linefeed
fields[-1] = fields[-1][:-1]
elements[fields[-1]] = fields[:-1]
Then you get a dictionary with the last name in the table as key and a
list of the other attributes as value.
Then, if you want to look for an attribute, just do:
for element in elements.items():
if 'j' in element[1]:
print element[0]
What do you think?
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] webcam secrets?
Hi Johnny, As someone already said, it could be possible to do that without going into any code, but assuming you want to do it by means of Python... I assume you're using Windows, are you trying to control another application (the one that came with your webcam)? are you trying to write a program that accesses the driver for your webcam? In any case, whatever you're trying to accomplish will have a lot to do with what the operating system allows you. May I suggest you take another program or exercise more related to programming before you become complicated with so mucho weird operating system interfaces? I suppose webcams are accessed through the TWAIN infterface. There is (old) support for python, here: http://twainmodule.sourceforge.net/docs/ Hugo johnny` walker wrote: i was wondering if there was a way to automatically take a picture from my webcam every oh say 5 minutes? is there anyway of doing this (im very new to programming languages.) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I'm puzzled
Hi Vincent, the program works with any input except when you just hit the enter key. To be able to understand why is the crash, take a look at what the interpreter tells you: File untitled.py, line 12, in ? elif a[0] == '-' and a[1:].isdigit(): IndexError: string index out of range IndexError is raised whan you try to access an element in a list or string, an element that does not exist. In the case where you only press enter, what is the content of a How many characters? (hint, you may try to print a before any evaluation... Hope that gets you going, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] python-based system programming and admin?
MMM strange needs... I'm thinking that perhaps allowing him to run idle and exporting X display to the Mac could be an option? I used to do perl on linux until I found Python, I find it very easy to run quick scripts and system stuff without having to learn BASH, sed, awk, etc separately, taht way I can do regexp, listings, recursion on directories, batch jobs, etc. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeout
Hi Frank, how can I break a loop after a certain amount of time has passed? If the loop actually does something, I've used time.time() in the past: start_time = time.time() timeout = 60 #seconds while True: do_something() if time.time() - start_time = timeout: break time.time() just keeps increasing as it reports the system's clock (in UNIX epoch time, just increasing seconds) Hope that helps, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] CPU Utilization
Hi,
top is very interactive so it would not be easy at all to parse.
I can suggest reading /proc/loadavg if you're in Linux.
proc(5) ('man 5 proc') says that /proc/loadavg is
The load average numbers give the number of jobs in
the run queue averaged over 1, 5 and 15 minutes.
They are the same as the load average numbers given
by uptime(1) and other programs.
It can be easily parsed with split()
Hope that helps,
Hugo
DS wrote:
I am implementing a computational cluster and am using a job controller
(for want of a better term) that contacts the worker computers,
determines how busy they currently are, and then assigns more work if
the worker computer is below a certain cpu utilization threshhold.
For the cpu threshhold, I've been thinking I'd have the worker computer
shell out to perform the top command, parse the results, and report
those values to the job controller.
Is there a better way, or more pythonic, way to do this?
Thanks
ds
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] bnf
mystring = 'laLA' mystring.upper() 'LALA' mystring.lower() 'lala' ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] python-ldap
Hi, Looks like they are just constants. There is really no point in printing or making any sense of their content, just use them as they are defined in the module. This is like a C #define But this is all LDAP specific... let's see: ## The next lines will also need to be changed to support your search requirements and directory baseDN = ou=Customers, ou=Sales, o=anydomain.com searchScope = ldap.SCOPE_SUBTREE SCOPE_SUBTREE is one of the avaliable search scopes. According to this(http://linuxjournal.com/article/6988) it should search for the object and its descendants.. if result_type == ldap.RES_SEARCH_ENTRY: result_set.append(result_data) Reading it as it is, looks like the result may be something different, but only those results that are of type RES_SEARCH_ENTRY are meaningful. That's why you check it. read, read, read. This is what I understand, not knowing crap about LDAP, and just using Google. Check the following docs: ` http://www.ldapman.org/ldap_rfcs.html http://www.cse.ohio-state.edu/cs/Services/rfc/rfc-text/rfc1823.txt Bingo! This is the LDAP application programming interface from which the Python LDAP implementation has been 'stolen' All these definitions are explained. For instance: Parameters are: ldThe connection handle; base The dn of the entry at which to start the search; scope One of LDAP_SCOPE_BASE, LDAP_SCOPE_ONELEVEL, or LDAP_SCOPE_SUBTREE, indicating the scope of the search; Upon successful completion, ldap_result() returns the type of the result returned in the res parameter. This will be one of the following constants. LDAP_RES_BIND LDAP_RES_SEARCH_ENTRY LDAP_RES_SEARCH_RESULT LDAP_RES_MODIFY LDAP_RES_ADD LDAP_RES_DELETE LDAP_RES_MODRDN LDAP_RES_COMPARE Google is your friend, and going through you may find most of your answers... Hope that help, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Lists with just an item
Probably due to the lacking of experience, but each time I code a datastructure I am never satisfied, and I have the feeling that I'm not on the right way.. The same thing happens to me. I actually have a very similar problem to yours now, and I'm rather considering a list of two-element tuples. Greetings, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Ellipsis syntax
Hi all, I have looked for any references of ellipsis '...' syntax for Python slices, but I keep finding the same BNF grammar in the LanguageRreference. Is there any page with examples on how to do this, or is this just very obscure? I remember reading something about this syntax somewhere, long ago. I don't even know how it is supposed to be used, but it is in the grammar... Any help would be appreciated. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Ellipsis syntax
Ok, now I know I don't need them just now *grin* Next time I will remember to search the newsgroup Now I think it was the perlish skeletons in my closet coming back to me. Thanks a lot for that, Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Overloading comparisons
Hi all, I defined an object wich describes a video clip, like this class VideoSegment: def __init__(self, filename): # Attributes that have to be present self.filename = filename The thing is, I will define an array of these objects for a cache, and would like to keep that array having less than 1000 elements. Periodically I will check it, and remove the oldest element. suppose I have the modification time as an argument. self.time = os.stat(self.filename).st_mtime I can define the following for sorting the array: def __cmp__(self, other): polymorph for comparisons if self.time other.time: return -1 elif self.time other.time: return 1 else: return 0 But then I want to test for existance doing if 'lala.avi' in myarray: and that has to be done by name. Is there any way this could work? My current __cmp__ of course treats objects with the same timestamp as identical objects. Any comments are greatly appreciates, maybe my OOP is just sloppy... Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Overloading comparisons
I know it is rude to reply to myself. But I found the answer and wanted to share it. I did the following test: class Lala: ... def __eq__(self, other): ... if self.name == other.name: ... return True ... ... def __cmp__(self, other): ... if self.time other.time: ... return -1 ... elif self.time other.time: ... return 1 ... else: ... return 0 ... ins0 = Lala() ins0.time = 11 ins0.name = 'myname' ins1 = Lala() ins1.time = 10 ins1.name = 'myname' ins1 == ins0 True ins0ins1 False ins1ins0 True #See? They test correctly for greater and lesser than (time) ... #but they test equal as to time. ... #I even tried sort, it works fine. The thing is to use the rich comparison functions. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Overloading comparisons
Hi Danny, That's nice. I do think I'm going this way I don't want the container to grow too big in memory, not bigger than 1k elements(it is a cache), but when deleting an element I need it to be the oldest files (again, because it is a cache) Thanks for the advice, I'm going this way. My OOP skills *are* sloppy... Hugo Danny Yoo wrote: I defined an object wich describes a video clip, like this class VideoSegment: def __init__(self, filename): # Attributes that have to be present self.filename = filename ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] question about serial coms
Hi Nephish, Are you using pyserial or rolling your own? Normally you can write and read to the /dev/ttySXX file at the same time; since they're special files, not ordinary files, the driver handles that. Handling both writing and reading in your program's flow control is a wholly different matter, though. You might need to use select() to avoid blocking. Are you using two completely different scripts for reding and writing? There is some valuable info, if not about python, in the Serial Programming howto, at: http://www.tldp.org/HOWTO/Serial-Programming-HOWTO/ Hugo nephish wrote: Hey there, i am developing on a linux computer with the serial module. Now, i already am able to recieve info from a serial RS232 device and process everything ok. What i need to do now is write to the serial device, but i also need to be able to not interrupt the script that is reading from it. I guess my question is, do i have to interrupt the reading script to write to the same RS232 device ? and if so, how do i do that? thanks, shawn ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] What does Python gain by having immutable types?
Quite often the only answer is just because. Some features are the way they are because that's Guido's pesonal preference. Others may disagree with him but it's his language and he gets to pick what he thinks is best - the benign dictator syndrome. There's also the issue that immutability is Python's way of dealing with passing by value and passing by reference. And that removing the difference between mutable and immutable objects would mutate (no pun intended) the language in a big way. Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How do I display a changing thing in text?
Hi Nathan, Take a look at string interpolation in the tutorial. I don't know what method you're following for learning Python, but I've found the 'official' tutorial a great resource, even when you already know Python, http://docs.python.org/tut/node9.html#SECTION00910 Nathan Pinno wrote: How do I display a changing thing (i.e.. the score of the game) in text? I think it has something to do with this key: %, but I forget how to do it. Can someone show me how to do it again? Thanks, Nathan Pinno ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Do I have to initialize TKInter before I can use it?
Hi Nathan, It is always better if you include what you're actually trying to do. I see you included one traceback error, but I see no reference to what you're coding or any of your code. In your case , it's likely that you did not import the tkMessageDialog module or something like this. But we had to find that out after two more posts, because neither your code example or error messages were in the original. Please, please read: http://www.catb.org/~esr/faqs/smart-questions.html Keep hacking away :) Hugo ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving project
If you do File... Save Then select the location for your file and just give it a name, a '.py' extension will be added to the file. It is not in a specific format, it is just a text file with a '.py' extension. From Explorer you will likely see just the name of the file. And after you save you'll see the coloring on your program, which helps you avoid programming mistakes. I'm assuming you're using Windows and not Linux. Hugo sener wrote: hi everyone, Firstly I am a new programmer on python. I am using Python 2.4.1 with IDLE 1.1.1 I can't save my poject in my computer. how can I save my projects and in which format I must save my projects. thanks a lot. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] What does Python gain by having immutable types?
I believe the deal is that it is impossible (or at least extremely inefficient)to keep track of any places where a mutable object was hashed at the time of mutating it, so that ALL hashes can be updated. When the object is immutable, it implies that the hash will not change unless the id changes. Hugo Would you expect dicta[tupb] to produce 34 or 45? And what of dicta[tupc]? I believe this issue is one of whether to hash by identity or content. When hashing, the implied promise is that all objects whose contents are the same should produce the same value, but one also expects one key to map to one value. Without immutable types, where the identity and the content are intertwined, you get counterintuitive behavior a la the above mini-example (in reality, when you put two immutable objects with the same content in a dictionary, they both map to the same value - the last one assigned). I'm sure someone more knowledgeable will come along and shed the bright light of understanding where my feeble candle flickers, but till then, HTH. -Orri ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Do I have to initialize TKInter before I can use it?
Hi Nathan, The interactive interpreter is your friend. I just displayed a simple dialog without creating a Tkinter App, complete with a mailoop or anything. But I won't tell you how... you need to import the module and then use one of its functions. But you need to try it yourself (be aware that this module only gives you basic dialogs, like a text message ona little window with an 'Accept' button...) Remember that you can use the dir() function and the help() function on the interactive interpreter. Hugo Nathan Pinno wrote: John, I learned it from the docs on pythonware.com - the introduction to TKInter - Standard Dialogs. Since it doesn't exist, how can I show a info box before the main part of my program? \ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How do I display a changing thing in text?
The interactive intepreter is you friend. Of course I'm using actual numbers instead of variables for the examples. Let's see IDLE 1.0.3 Computer = %1.0d Player = %1.0d (1,2) Traceback (most recent call last): File pyshell#0, line 1, in -toplevel- Computer = %1.0d Player = %1.0d (1,2) TypeError: 'str' object is not callable H what is the problem? Computer = %1.0d Player = %1.0d%(1,2) 'Computer = 1 Player = 2' Here you go. You were missing the % sign after the string, with in this case is the operator... Hugo Nathan Pinno wrote: Hugo and all, So in order to write what I wanted the correct code would be: Computer = %1.0d Player = %1.0d (a,b) Am I correct or is this wrong? Nathan Pinno -Original Message- From: Hugo González Monteverde [mailto:[EMAIL PROTECTED] Sent: November 14, 2005 8:27 PM To: Nathan Pinno Cc: Tutor mailing list Subject: Re: [Tutor] How do I display a changing thing in text? Hi Nathan, Take a look at string interpolation in the tutorial. I don't know what method you're following for learning Python, but I've found the 'official' tutorial a great resource, even when you already know Python, http://docs.python.org/tut/node9.html#SECTION00910 Nathan Pinno wrote: How do I display a changing thing (i.e.. the score of the game) in text? I think it has something to do with this key: %, but I forget how to do it. Can someone show me how to do it again? Thanks, Nathan Pinno -- -- ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Question about resetting values
There may be more than one way to have it get a zero value. But in languages like Python readability and clarity are valued, and clearly var = 0 is the clearest way to do it, although var = var^var comes to mind, *grin* Hugo Nathan Pinno wrote: Never mind all. I was just being stupid as usual. I thought that there might be a Python command for resetting and wanted to find out if that was the case. - Original Message - From: Alan G [EMAIL PROTECTED] To: Nathan Pinno [EMAIL PROTECTED]; Tutor mailing list tutor@python.org Sent: Tuesday, August 02, 2005 2:45 PM Subject: Re: [Tutor] Question about resetting values I am writing a Blackjack program, and was wondering how to reset the values to zero, e.g. cash = 0? Yes, that's how you do it. Now what is the bit you don't understand? Alan G Author of the Learn to Program web tutor http://www.freenetpages.co.uk/hp/alan.gauld ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] [Fwd: Re: Spanish text in BS problem]
Hi Ismael,
I'm glad you found the answer. It is very enlightening as I thought I
had to do with locale and did some tests without getting the problem (I
do not have BS installed now)
As I speak Spanish this had got me worried. :/
Hugo
Ismael Garrido wrote:
Found the problem myself.
(look down)
Ismael Garrido wrote:
This is the script:
import BeautifulSoup
import os
a = open(zona.htm)
text = a.readlines()
a.close()
BS = BeautifulSoup.BeautifulSoup(str(text))
Apparently, str(text) is the cause of the problem. If instead I do:
.join(text) it all works allright. I guess this is because str
converts 'ó' to '\xf3' while .join() does not change the strings in
any way. Now the output from BS makes sense.
Bye,
Ismael
for ed in BS('span', {'class':'ed_ant_fecha'}):
fecha = ed.next.split( )[1].replace(.,-)
urlynombre = ed.findNextSibling().findNextSibling().findNextSibling()
url = 'http://espectador.com/' + urlynombre.get('href')
nombre = urlynombre.next.next
print url
print D:/dolina/+fecha, nombre
print
###end
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] python watchfolder as daemon
Hi, I do this all the time. I use a recipe, and import a daemon module. The module is here: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/278731 in your script, just do import daemon and daemon.createDaemon() Works like a charm. Hugo Frank Hoffsümmer wrote: Hello all, I found this gem of a python recipe that allows me to monitor a hierarchy of folders on my filesystem for additions / changes / removals of files: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/215418 I would like to monitor a folder hierarchy using this script but now I wonder what would be the best way to have this watchfolder script running at all times in the background? nohup python watchfolder.py myfolder ? would that be suitable?? or is there a way to launch a process like that from python that detaches itself from the shell? what would be the best way, any insight or recommendation is very much appreciated thanks, -frank ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] lists strings and files
Have you tried pickling them? If you want it to be flattened, so that result is: [fields[1], fields[2], fields[3]] instead of [[fields[1], fields[2], fields[3]]] you should use the extend method instead of the append method. Hugo Michael Haft wrote: Hello, thanks for all the help with lists and strings, the list I have has nested sublists in it though. How do I remove these or is there a way to convert from lists to strings without removing them? The code looks something like: result = [] data = [fields[1] fields[3] fields[7]] result.append(data) which gives a list containing 12 sublists Appologies if the code isn't quite right I'm stuck on a library computer in a strange German university and can't use my memory stick to check the exact code. Mike ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Python persistent webserver?
Looks like CherryPy is a good candidate. Take a look at: www.cherrypy.org` it can be plugged into Apache, and if persistency is what you need, you'll get it. There are nice examples for getting started. Hugo Howard Kao wrote: Hi all, I know the subject is confusing but I don't know how to describe what I would like to ask concisely. Basically I would like to have a program (or server or whatever) take an HTTP POST method (which contains some information, maybe even an XML file) from a client, process these XML/information, and then generate an XML to send back to the client. Currently the environment it has to be done under is Apache on Linux. I am thinking that it may have to be a persistent running program... However it seems a daunting task for a Python noob like me. Preferably it doesn't need threading and need not to be sophiscated at all, as long as it can take the request, process info and send stuff back to a client. I have no idea how to do this at all and couldn't find much information. The Base, Simple, CGI HTTPServer modules all seem a little lacking , but that's probably due to my lack of py-fu to start with... Any suggestions would be appreciated. Many thanks! ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] lists and strings
Hi Mike,
Converting an (almost)arbitrary object into a string is what the Pickle
module does. CPickle is faster. Take a look into into it in the docs.
Here's an example:
import cPickle
lala = [1, 2, 3, 'four', 'V']
lala
[1, 2, 3, 'four', 'V']
fileo = open('lala.pkl', 'w')
cPickle.dump(lala, fileo)
fileo.close()
fileo = open('lala.pkl', 'r')
serialized_data = fileo.read()
serialized_data
(lp1\nI1\naI2\naI3\naS'four'\np2\naS'V'\na.
fileo.seek(0)
recovered = cPickle.load(fileo)
recovered
[1, 2, 3, 'four', 'V']
See the docs and feel free to ask if there is some part oyu do not
understand.
Hope it helps!
Hugo
Mike Haft wrote:
Hello,
I've been working on a problem and have now sorted most of it (thanks
to some help from the list).
All the ways of writing data to a file I know keep telling me that lists
can't be written to the file. I'm trying to convert data from one set of
files into files of a different format. But the easiest way to get the
data from the first set of files is in a list(s).
So, is there any way to convert lists to strings? Or a way to write lists
to a file?
Thanks
Mike
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Exit from program early
or raise SystemExit Hugo Johan Geldenhuys wrote: Try using 'sys.exit()' where you want the script to stop if you haven't supplied enough arguments. in you example, it looks like it will go on to the else anyway AND print the string at the end. HTH, Johan Roy Bleasdale wrote: Hi In the example below I would like the program to stop if I forgot to provide an argument . Though I could do all my processing indented under the else statement, I was wondering if there was a command that would allow me to halt the program execution early. Regards, Roy # Example program - Test for valid argument import sys if len(sys.argv) 2: print opps missing an argument # Nice if I could stop and exit program here else: print Argument provided!! # Looking good so go do some stuff print Done some stuff ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] pack
pack is a method of Tkinter widget that needs to be called in order to have it displayed with the current geometry manager(which per default is the pack method) A geometry manager is just a way for arranging widgets into a window. Another geometry manager is grid If you don't specify anything, the widget will simply not be displayed.. see here: http://effbot.org/tkinterbook/pack.htm Hugo Shi Mu wrote: what does pack mean in the following code? # File: hello1.py from Tkinter import * root = Tk() w = Label(root, text=Hello, world!) w.pack() root.mainloop() ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Capture command output
Hi,
Here's the docs for the popen2 module in python 2.2, the Popen2 object
allows you to get the pid. The popen2() call allows you to get the
output in a filehandle.
http://www.python.org/doc/2.2.3/lib/module-popen2.html
You cannot run any function at all in your script after you do the exec
call, it is no longer your program, but the one you exec-ed. popen
actually runs the subprocess, you don't have to call it manually. Popen
is the most used way to get the output, and looks like it is the only
one in Python 2.2.
Here's an example.
import popen2
myobj = popen2.Popen3('/bin/ls')
dir(myobj)
['__doc__', '__init__', '__module__', '_run_child', 'childerr',
'fromchild', 'pid', 'poll', 'sts', 'tochild', 'wait']
myobj.pid
3033
output = myobj.fromchild.read()
output
'Changelog\nblankcursor\ndaemon.py\ndaemon.pyc\nl_index.txt\nl_sec.txt\nloadlin16c.txt\nloadlin16c.zip\nmypipa\nnewlooper.py\nxorg.conf.new\n'
myobj.wait()
0
Johan Geldenhuys wrote:
The version of python that I have is 2.2.2 and I can't upgrade, sorry.
As far as I know this only from version 2.4.2??
Johan
Kent Johnson wrote:
Johan Geldenhuys wrote:
I've been musy with the os command on how to kill a process. That's been
sorted out to an extend. Many thanks for your input.
Now I have a question in the same direction:
I use os.execpv(cmd, [cmd, args]). That executes the command that have
output. This was the best way of getting the pid and killing the process
after a certain time.
How do I capture that output to a file?
Can I use os.popen() or something like that after I did the os.execvp()
execution or is there a standard way of putting any output in a file/
Have you tried using subprocess.Popen()? It supports capturing output of the
child process and it gives access to the pid of the child.
Kent
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] os command
In UNIX, you use the fork() exec() technique for starting a new process, from the very first process(init) onwards. The os.system() uses a shell to do that, or you may do it yourself (in your script) A command is just an executable file running(process), unless you've got a library function that does just that, then you could do what you must without creating a new process. Probably your best bet would be to use the subprocess module. It was designed around the limitations of the previous methods. Take a look at what oyu can do with it at: http://www.python.org/doc/2.4.2/lib/module-subprocess.html For example, the pid of the command would be available at the pid atribute of a subprocess instance. p.pid Hugo Johan Geldenhuys wrote: Sorry for the late reply, But is it necessary to use a child process? I don't want to execute the command in another process. What happens with the parent process and how do I execute my command in the parent process? Thanks Hugo González Monteverde wrote: Hi, os.system will return the errorval of the application. You need to 1) get the pid of the child process 2) kill it using os.kill(os.SIGTERM) 3) reap the killed process This is all in unix/linux, of course. what I do (untested, please check order of args and correct usage of exec): pid = os.fork() if pid == 0: #child process os.execvp(tcpdump, tcpdump, -n, -i, eth0) else: #parent time.sleep(5) os.kill(pid, os.SIGTERM) os.waitpid(pid, 0) #wait for process to end Johan Geldenhuys wrote: I have script that calls a system command that I want to run for 5 minutes. import os cmd = 'tcpdump -n -i eth0' os.system(cmd) I can start a timer after the cmd is issued, but I don't know how to send a control signal to stop the command after I issued it. This is normally from the shell ^c. This cmd my run in more than one thread on different interfaces and I don't whant all of then stopped at once. I think the best way is to make a thread for each interface where the cmd can be issued and stopped without the danger of stopping he wrong thread. Can anybody help? Thanks Johan ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] os command
Hi
Johan Geldenhuys wrote:
Hugo,
I see that 'os.execcvp()' doesn't actually make two seperate processes.
This is what I have working now:
import os, signal, time
pid = os.fork()
print 'pid; ',pid
if pid == 0: #child process
#os.execvp('tcpdump', ['tcpdump', '-i modem0 cap1.txt'])
os.execvp('ping', ['ping', '127.0.0.1 -c 30 cap.txt'])
The following line (sleep)is superluous, as it is no longer your python
script after calling exec()
Your process (in this case the child process)is replaced with a copy of
ping in memory.
time.sleep(5)
kill(pid)
def kill(pid, signal=signal.SIGTERM):
print trying to kill pid..., pid
os.kill(pid, signal)
os.waitpid(pid, 0)
print Killed %d%pid
The ping command is executed but the part where it must put the replies
in the file is not recognized. How do I use the addisional arguments to
be seen?
Mmm no, this line:
os.execvp('ping', ['ping', '127.0.0.1 -c 30 cap.txt'])
uses *shell redirection*.. guess who has to interpret the whole thing..
As you are using no shell, the '' argument is passed to the ping
program, which knows nothing of handling it the way you expect it.
What you're doing is equivalent to (in my workstation)
[EMAIL PROTECTED]:~# ping 192.168.0.8 cap.txt
ping: unknown host
You have to call a shell if you want to use redirection, otherwise you
will have to use python to send all of ping's output to a file (which
would be a nice exercise, IMHO ;) )
Hugo
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
