Re: Loading a Python collection from an text-file
Ken Starks wrote:
Ilias Lazaridis wrote:
within a python script, I like to create a collection which I fill with
values from an external text-file (user editable).
How is this accomplished the easiest way (if possible without the need
of libraries which are not part of the standard distribution)?
something like:
text-file:
{peter, 16},
{anton, 21}
-
within code:
users.load(text-file.txt)
for user in users
user.name
user.age
[...]
the solutions below seems to be the most compact one.
this, or the suggested CSV module within the other messages.
thank's to everyone for the feedback.
[...]
If you want to use a plain text format, keep it simple. I would
separate the two fields with tab (thus permit a comma within a field)
and allow 'comment' lines that start with a hash.
You don't need the braces, or the end-of-line comma you included.
# snip 'text-file.txt'
# name and age on one line separated by tab
Jonny 8
Mary87
Moses 449
# end-snip 'text-file.txt'
Then:
import string
class user:
def __init__(self,name,age):
self.name=name
self.age=int(age) # or a float, or a time-interval, or date-of-birth
def show(self):
print %s is aged %s % (self.name, self.age)
if __name__==__main__:
users=[]
filename=text-file.txt
fieldsep=\t
F=open(filename,r)
Lines=F.readlines()
for L0 in Lines:
L1=string.strip(L0)
if not L1.startswith(#):
Record=string.split(L1,fieldsep)
# insert error handling/validation here
users.append(user(Record[0],Record[1]))
F.close()
for user in users:
user.show()
.
--
http://lazaridis.com
--
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Re: Loading a Python collection from an text-file
perhapse consider using the pickle module? http://docs.python.org/lib/module-pickle.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
On Mon, 23 Jan 2006 21:00:55 +0200, Ilias Lazaridis [EMAIL PROTECTED] wrote:
within a python script, I like to create a collection which I fill with
values from an external text-file (user editable).
How is this accomplished the easiest way (if possible without the need
of libraries which are not part of the standard distribution)?
something like:
text-file:
{peter, 16},
{anton, 21}
-
within code:
users.load(text-file.txt)
for user in users
user.name
user.age
.
--
http://lazaridis.com
I'd use a CSV text file, maybe something like (only tested as far as you see!):
for_ilias_lazaridis.py --
import csv, types
class Fields(object):
def __init__(self, kvpairs): self.__dict__.update(kvpairs)
class Users(object):
def __init__(self):
self.userlist=[]
def load(self, lineiter):
if isinstance(lineiter, basestring):
lineiter = open(lineiter) # assume it's a file path
csvit = csv.reader(lineiter)
self.colnames = colnames = csvit.next()
typenames = csvit.next()
self.coltypes =coltypes = [getattr(types, name.capitalize()+'Type')
for name in typenames]
for row in csvit:
self.userlist.append(Fields(zip(colnames, (t(s) for t,s in
zip(coltypes, row)
def __iter__(self): return iter(self.userlist)
def test():
import StringIO
f = StringIO.StringIO(\
name,age
String,Int
peter,16
anton,21
)
users = Users()
users.load(f)
for user in users:
print user.name, user.age
for user in users:
for name in users.colnames:
print '%s=%s,'%(name, getattr(user, name)),
print
if __name__ == '__main__': test()
---
Output:
[ 4:47] C:\pywk\clppy24 for_ilias_lazaridis.py
peter 16
anton 21
name=peter, age=16,
name=anton, age=21,
(the first for user in users loop presumes knowledge of the field names name
and age.
The second gets them automatically from the names loaded in the load method from
the first line of the text file. The second line expects type names as you see
in the types module, except without the Type suffix.
Perhaps you can adapt for your purposes.
Regards,
Bengt Richter
--
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Re: Loading a Python collection from an text-file
Seeing as we're suggesting alternatives, ConfigObj is great for hand readable/writable data persistence. You can use validate and ConfigPersist for automatic type conversion. You can persist (basically) all the standard datatypes using this. The syntax is usually more 'familiar' than Yaml, but it's not as flexible. http://www.voidspace.org.uk/python/configobj.html All the best, Fuzzyman http://www.voidspace.org.uk/python/index.shtml -- http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
Ilias Lazaridis wrote: within a python script, I like to create a collection which I fill with values from an external text-file (user editable). If a spreadsheet like layout fits, use the csv module and a plain comma separated file. Then the end user can also use e.g. Excel to edit the data. -- http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
Sure, it's just a Python module with variables in it. I wouldn't try to teach my users Python syntax though. not to mention the security risks -- http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
Ido Yehieli wrote: Sure, it's just a Python module with variables in it. I wouldn't try to teach my users Python syntax though. not to mention the security risks you mean all the things they can do from inside python that they cannot do from the command line ? /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
[EMAIL PROTECTED] wrote: another approach (probably frowned upon, but it has worked for me) is to use python syntax (a dictionary, say, or a list) and just import (or reload) the file this sounds good. can I import a whole collection of instances this way? - (thanks for all the other answers within this thread). . -- http://lazaridis.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
another approach (probably frowned upon, but it has worked for me) is to use python syntax (a dictionary, say, or a list) and just import (or reload) the file -- http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
Take a look at ConfigParser module. The format of the file would be
something like:
[members]
peter=16
anton=21
People are accustomed to this format file (windows .ini format).
-Larry
Ilias Lazaridis wrote:
within a python script, I like to create a collection which I fill with
values from an external text-file (user editable).
How is this accomplished the easiest way (if possible without the need
of libraries which are not part of the standard distribution)?
something like:
text-file:
{peter, 16},
{anton, 21}
-
within code:
users.load(text-file.txt)
for user in users
user.name
user.age
.
--
http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
Maybe YAML is what youre looking for... http://yaml.org -- http://mail.python.org/mailman/listinfo/python-list
Re: Loading a Python collection from an text-file
Ilias Lazaridis wrote:
within a python script, I like to create a collection which I fill with
values from an external text-file (user editable).
How is this accomplished the easiest way (if possible without the need
of libraries which are not part of the standard distribution)?
something like:
text-file:
{peter, 16},
{anton, 21}
-
within code:
users.load(text-file.txt)
for user in users
user.name
user.age
.
What I do for this kind of work is to use a gnumeric spreadsheet
which saves the data in a simple xml format. xml is much less
error-prone than plain text.
Google for, and study 'The gnumeric file format' by David Gilbert.
You need to know how to unzip the file, and how to write a SAX parser.
If you want to use a plain text format, keep it simple. I would
separate the two fields with tab (thus permit a comma within a field)
and allow 'comment' lines that start with a hash.
You don't need the braces, or the end-of-line comma you included.
# snip 'text-file.txt'
# name and age on one line separated by tab
Jonny 8
Mary87
Moses 449
# end-snip 'text-file.txt'
Then:
import string
class user:
def __init__(self,name,age):
self.name=name
self.age=int(age) # or a float, or a time-interval, or date-of-birth
def show(self):
print %s is aged %s % (self.name, self.age)
if __name__==__main__:
users=[]
filename=text-file.txt
fieldsep=\t
F=open(filename,r)
Lines=F.readlines()
for L0 in Lines:
L1=string.strip(L0)
if not L1.startswith(#):
Record=string.split(L1,fieldsep)
# insert error handling/validation here
users.append(user(Record[0],Record[1]))
F.close()
for user in users:
user.show()
--
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