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Re: Sort lines in a plain text file alphanumerically

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  Re: Sort lines in a plain text file alphanumerically Joshua Landau <joshua@landau.ws> - 2013-08-06 04:12 +0100
    Re: Sort lines in a plain text file alphanumerically alex23 <wuwei23@gmail.com> - 2013-08-06 13:49 +1000
      Re: Sort lines in a plain text file alphanumerically alex23 <wuwei23@gmail.com> - 2013-08-06 13:51 +1000
      Re: Sort lines in a plain text file alphanumerically alex23 <wuwei23@gmail.com> - 2013-08-06 14:33 +1000
      Re: Sort lines in a plain text file alphanumerically Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-08-06 06:40 -0400

#51995 — Re: Sort lines in a plain text file alphanumerically

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On 6 August 2013 03:00, Devyn Collier Johnson <devyncjohnson@gmail.com>wrote:

> I am wanting to sort a plain text file alphanumerically by the lines. I
> have tried this code, but I get an error. I assume this command does not
> accept newline characters.
>

HINT #1: Don't assume that without a reason. It's wrong.


> >>> file = open('/home/collier/pytest/**sort.TXT', 'r').read()
>

HINT #2: Don't lie. "file" is not a file so you probably shouldn't call it
one. It's the contents of a file object.


> >>> print(file)
> z
> c
> w
> r
> h
> s
> d
>
>
> >>> file.sort() #The first blank line above is from the file. I do not
> know where the second comes from.
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> AttributeError: 'str' object has no attribute 'sort'
>

HINT #3: *Read*. What does it say?

    AttributeError: 'str' object has no attribute 'sort'

Probably your problem, then, is that a 'str' object has no attribute
'sort'. That's what it says.

"file" is a "'str' object". You are accessing the 'sort' attribute which it
doesn't have.

I had the parameters (key=str.casefold, reverse=True), but I took those out
> to make sure the error was not with my parameters.
>

HINT #4: Don't just guess what the problem is. The answer is in the error.


> Specifically, I need something that will sort the lines. They may contain
> one word or one sentence with punctuation. I need to reverse the sorting
> ('z' before 'a'). The case does not matter ('a' = 'A').
>
> I have also tried this without success:
>
> >>> file.sort(key=str.casefold, reverse=True)
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> AttributeError: 'str' object has no attribute 'sort'
>



So you want to sort your string by lines. Rather than trying to abuse a
.sort attribute that patently doesn't exist, just use sorted OR convert to
a list first.

    sorted(open('/home/collier/pytest/**sort.TXT'), key=str.casefold,
reverse=True)

Because it's bad to open files without a with unless you know what you're
doing, use a with:

    with open('/home/collier/pytest/**sort.TXT') as file:
        sorted(file, key=str.casefold, reverse=True)

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#51997

On 6/08/2013 1:12 PM, Joshua Landau wrote:
> Because it's bad to open files without a with unless you know what
> you're doing, use a with:
>
>      with open('/home/collier/pytest/__sort.TXT') as file:
>          sorted(file, key=str.casefold, reverse=True)

Shouldn't that be:

     with open('/home/collier/pytest/__sort.TXT') as file:
         data = file.readlines()
         sorted(data, key=str.casefold, reverse=True)

I'm tempted to say "HINT #5: don't provide a solution without testing it 
first" but that would be pretty obnoxious.

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#51998

On 6/08/2013 1:49 PM, alex23 wrote:
> Shouldn't that be:
>
>      with open('/home/collier/pytest/__sort.TXT') as file:
>          data = file.readlines()
>          sorted(data, key=str.casefold, reverse=True)
>
> I'm tempted to say "HINT #5: don't provide a solution without testing it
> first" but that would be pretty obnoxious.

Even more so when I got it wrong myself :)

     data = sorted(file.readlines(), key=str.casefold, reverse=True)

I can never remember which one sorts in place and which doesn't.

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#51999

On 6/08/2013 1:49 PM, alex23 wrote:
> On 6/08/2013 1:12 PM, Joshua Landau wrote:
>> Because it's bad to open files without a with unless you know what
>> you're doing, use a with:
>>
>>      with open('/home/collier/pytest/__sort.TXT') as file:
>>          sorted(file, key=str.casefold, reverse=True)
>
> Shouldn't that be:
>
>      with open('/home/collier/pytest/__sort.TXT') as file:
>          data = file.readlines()
>          sorted(data, key=str.casefold, reverse=True)

Hmm, I take that back entirely. Your version does work. Weirdly, I tried 
yours under both 2.7 & 3.2 without it working at all, but a subsequent 
attempt did. Sorry for the noise.

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#52025

On 08/05/2013 11:49 PM, alex23 wrote:
> On 6/08/2013 1:12 PM, Joshua Landau wrote:
>> Because it's bad to open files without a with unless you know what
>> you're doing, use a with:
>>
>>      with open('/home/collier/pytest/__sort.TXT') as file:
>>          sorted(file, key=str.casefold, reverse=True)
>
> Shouldn't that be:
>
>     with open('/home/collier/pytest/__sort.TXT') as file:
>         data = file.readlines()
>         sorted(data, key=str.casefold, reverse=True)
>
> I'm tempted to say "HINT #5: don't provide a solution without testing 
> it first" but that would be pretty obnoxious.
I tried Joshua's suggestion in Python3.3 and it worked. What version of 
Python are you using?

DCJ

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