Sort lines in a text file

John Machin sjmachin at
Sun Jul 22 08:04:56 CEST 2007

On Jul 22, 1:03 pm, leegold <goldt... at> wrote:
> say I have a text file:
> zz3 uaa4a ss 7 uu
>   zz 3 zzzz66 ppazz9
> aaaaaaaaa00000zz0
> I want to sort the text file. I want the key to be the number after
> the two "zz".  Or I guess a string of two zz then a number....So
> that's 3, 9, 0
> I'm trying to say that I want to sort lines in a file based on a
> regular expression. How could I do that in Python? I'm limited to
> Python 2.1, I can't add any 2nd party newer tools.

To save anybody who's tempted to write the whole shebang for you,
please specify which part(s) of the exercise you are having problems
(a) reading lines from a file
(b) extracting a sort key from a line [presuming "number" means
"positive integer"; what do you want to do if multiple lines have the
same number? what if no number at all"]
(c) creating a list of tuples, where each tuple is (key,
(d) sorting the list
(e) creating the output file from the sorted list.

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