Re: May I drop list bracket from list?
On 04/23/2015 06:11 AM, subhabrata.bane...@gmail.com wrote:
Dear Group,
I am trying to read a list of files as
list_of_files = glob.glob('C:\Python27\*.*')
Now I am trying to read each one of them,
convert into list of words, and append to a list
as.
list1=[]
for file in list_of_files:
print file
fread1=open(file,"r").read()
fword=fread1.split()
list1.append(fword)
Here the list is a list of lists, but I want only one list not
list of lists.
I was thinking of stripping it as, str(list1).strip('[]')
but in that case it would be converted to string.
Is there a way to do it. I am using Python27 on Windows7 Professional.
Apology for an indentation error.
If anybody may please suggest.
You're first problem is the name of your variable. fword implies it's a
string, but it's really a list. So when you do:
list1.append(fword)
you're appending a list to a list, which gives you nested lists. Sounds
like you want
list1.extend(fword)
--
DaveA
--
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Re: May I drop list bracket from list?
On Thu, 23 Apr 2015 09:12 pm, Jean-Michel Pichavant wrote: > If both list1 and fword are lists, you can also write > > list1 = list1 + fword > or > list1 += fword You can, but you shouldn't since it risks being very slow, especially the first version. Repeated list addition has quadratic behaviour. It's okay if you only add a few lists, but if there are thousands or millions of them, it will be horribly slow. Using extend guarantees to modify the list in place and avoid unnecessary copying of data. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: May I drop list bracket from list?
Jean-Michel Pichavant wrote: > - Original Message - >> From: "Peter Otten" <__pete...@web.de> >> To: python-list@python.org >> Sent: Thursday, 23 April, 2015 12:26:41 PM >> Subject: Re: May I drop list bracket from list? >> >> subhabrata.bane...@gmail.com wrote: >> >> > Dear Group, >> > >> > list1=[] >> > for file in list_of_files: >> > print file >> > fread1=open(file,"r").read() >> > fword=fread1.split() >> > list1.append(fword) >> > >> > Here the list is a list of lists, but I want only one list not >> > list of lists. >> There is also a dedicated extend() method that takes a list (actually >> an >> iterable) and appends all items in that list: >> >> list1.extend(fword) > > If both list1 and fword are lists, you can also write > > list1 = list1 + fword > or > list1 += fword Yes, the can of worms is bottomless ;) -- https://mail.python.org/mailman/listinfo/python-list
Re: May I drop list bracket from list?
- Original Message - > From: "Peter Otten" <__pete...@web.de> > To: python-list@python.org > Sent: Thursday, 23 April, 2015 12:26:41 PM > Subject: Re: May I drop list bracket from list? > > subhabrata.bane...@gmail.com wrote: > > > Dear Group, > > > > list1=[] > > for file in list_of_files: > > print file > > fread1=open(file,"r").read() > > fword=fread1.split() > > list1.append(fword) > > > > Here the list is a list of lists, but I want only one list not > > list of lists. > There is also a dedicated extend() method that takes a list (actually > an > iterable) and appends all items in that list: > > list1.extend(fword) If both list1 and fword are lists, you can also write list1 = list1 + fword or list1 += fword JM -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. -- https://mail.python.org/mailman/listinfo/python-list
Re: May I drop list bracket from list?
subhabrata.bane...@gmail.com writes:
> I am trying to read a list of files as
> list_of_files = glob.glob('C:\Python27\*.*')
> Now I am trying to read each one of them,
> convert into list of words, and append to a list
> as.
>
> list1=[]
> for file in list_of_files:
> print file
> fread1=open(file,"r").read()
> fword=fread1.split()
> list1.append(fword)
>
> Here the list is a list of lists, but I want only one list not
> list of lists.
You probably want list.extend(fword) here. Python's ternimology is a
little quirky here -- in some other languages (ntable the mother of all
list langiages, Lisp), the append function does what Python's extend
does.
--
Ben.
--
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Re: May I drop list bracket from list?
subhabrata.bane...@gmail.com wrote:
> On Thursday, April 23, 2015 at 3:57:28 PM UTC+5:30, Peter Otten wrote:
>>
>>
>> > Dear Group,
>> >
>> > I am trying to read a list of files as
>> > list_of_files = glob.glob('C:\Python27\*.*')
>> > Now I am trying to read each one of them,
>> > convert into list of words, and append to a list
>> > as.
>> >
>> > list1=[]
>> > for file in list_of_files:
>> > print file
>> > fread1=open(file,"r").read()
>> > fword=fread1.split()
>> > list1.append(fword)
>> >
>> > Here the list is a list of lists, but I want only one list not
>> > list of lists.
>> >
>> > I was thinking of stripping it as, str(list1).strip('[]')
>> >
>> > but in that case it would be converted to string.
>> >
>> > Is there a way to do it. I am using Python27 on Windows7 Professional.
>> > Apology for an indentation error.
>> >
>> > If anybody may please suggest.
>>
>> You have to understand that the append() method always appends a single
>> item to the list, be that a string or a list or whatever. If you want to
>> append words in a list to the list the logical approach is therefore to
>> loop over the words and invoke append for every word
>>
>> for word in fword:
>> list1.append(word)
>>
>> There is also a dedicated extend() method that takes a list (actually an
>> iterable) and appends all items in that list:
>>
>> list1.extend(fword)
>
> Thanks Peter. I tried an example,
>>> ll = [['a'], ['b'], ['c']]
l = [x for y in ll for x in y]
>
> I would try your one,too.
>
> Regards,
> Subhabrata Banerjee.
The expression
[x for y in ll for x in y]
is called "list comprehension" and is syntactic sugar for
l = []
for y in ll:
for x in y:
l.append(x)
I suggest that you forget about list comprehensions until you are
comfortable with the traditional approach that uses for loops. Once you have
understood that the translation into list comprehensions in situations where
it looks better is mechanical.
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Re: May I drop list bracket from list?
On Thursday, April 23, 2015 at 3:57:28 PM UTC+5:30, Peter Otten wrote:
>
>
> > Dear Group,
> >
> > I am trying to read a list of files as
> > list_of_files = glob.glob('C:\Python27\*.*')
> > Now I am trying to read each one of them,
> > convert into list of words, and append to a list
> > as.
> >
> > list1=[]
> > for file in list_of_files:
> > print file
> > fread1=open(file,"r").read()
> > fword=fread1.split()
> > list1.append(fword)
> >
> > Here the list is a list of lists, but I want only one list not
> > list of lists.
> >
> > I was thinking of stripping it as, str(list1).strip('[]')
> >
> > but in that case it would be converted to string.
> >
> > Is there a way to do it. I am using Python27 on Windows7 Professional.
> > Apology for an indentation error.
> >
> > If anybody may please suggest.
>
> You have to understand that the append() method always appends a single item
> to the list, be that a string or a list or whatever. If you want to append
> words in a list to the list the logical approach is therefore to loop over
> the words and invoke append for every word
>
> for word in fword:
> list1.append(word)
>
> There is also a dedicated extend() method that takes a list (actually an
> iterable) and appends all items in that list:
>
> list1.extend(fword)
Thanks Peter. I tried an example,
>> ll = [['a'], ['b'], ['c']]
>>> l = [x for y in ll for x in y]
I would try your one,too.
Regards,
Subhabrata Banerjee.
--
https://mail.python.org/mailman/listinfo/python-list
Re: May I drop list bracket from list?
subhabrata.bane...@gmail.com wrote:
> Dear Group,
>
> I am trying to read a list of files as
> list_of_files = glob.glob('C:\Python27\*.*')
> Now I am trying to read each one of them,
> convert into list of words, and append to a list
> as.
>
> list1=[]
> for file in list_of_files:
> print file
> fread1=open(file,"r").read()
> fword=fread1.split()
> list1.append(fword)
>
> Here the list is a list of lists, but I want only one list not
> list of lists.
>
> I was thinking of stripping it as, str(list1).strip('[]')
>
> but in that case it would be converted to string.
>
> Is there a way to do it. I am using Python27 on Windows7 Professional.
> Apology for an indentation error.
>
> If anybody may please suggest.
You have to understand that the append() method always appends a single item
to the list, be that a string or a list or whatever. If you want to append
words in a list to the list the logical approach is therefore to loop over
the words and invoke append for every word
for word in fword:
list1.append(word)
There is also a dedicated extend() method that takes a list (actually an
iterable) and appends all items in that list:
list1.extend(fword)
--
https://mail.python.org/mailman/listinfo/python-list
May I drop list bracket from list?
Dear Group,
I am trying to read a list of files as
list_of_files = glob.glob('C:\Python27\*.*')
Now I am trying to read each one of them,
convert into list of words, and append to a list
as.
list1=[]
for file in list_of_files:
print file
fread1=open(file,"r").read()
fword=fread1.split()
list1.append(fword)
Here the list is a list of lists, but I want only one list not
list of lists.
I was thinking of stripping it as, str(list1).strip('[]')
but in that case it would be converted to string.
Is there a way to do it. I am using Python27 on Windows7 Professional.
Apology for an indentation error.
If anybody may please suggest.
Regards,
Subhabrata Banerjee.
--
https://mail.python.org/mailman/listinfo/python-list
