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Re: pylint woes

Path csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Subject Re: pylint woes
Date Sun, 8 May 2016 11:36:26 +1000
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On Sun, May 8, 2016 at 11:16 AM, DFS <nospam@dfs.com> wrote:
> On 5/7/2016 1:01 PM, Chris Angelico wrote:
>> The suggestion from a human would be to use zip(), or possibly to
>> change your data structures.
>
>
> Happens like this:
>
> address data is scraped from a website:
>
> names = tree.xpath()
> addr  = tree.xpath()
>
> I want to store the data atomically, so I parse street, city, state, and zip
> into their own lists.
>
> "1250 Peachtree Rd, Atlanta, GA 30303
>
> street = [s.split(',')[0] for s in addr]
> city   = [c.split(',')[1].strip() for c in addr]
> state  = [s[-8:][:2] for s in addr]
> zipcd  = [z[-5:] for z in addr]

So you're iterating over addr lots of times, and building separate
lists. As an alternative, you could iterate over it *once*, and have a
single object representing an address.

> Why is it better to zip() them up and use:
>
> for item1, item2, item3 in zip(list1, list2, list3):
>      do something with the items
>
> than
>
>
> for j in range(len(list1)):
>    do something with list1[j], list2[j], list3[j], etc.

Because 'j' is insignificant here, as is the length of the list. What
you're doing is iterating over three parallel lists - not counting
numbers. Imagine that, instead of lists, you just have *sequences* -
ordered collections of things. You can follow a recipe without knowing
the numbers of the individual lines; you just need to know the
sequence. Here, iterate over this collection:

* Collect ingredients.
* Cream the butter and the sugar.
* Sift the salt into the flour.
* Fold the mixture into an origami crane.

These instructions work whether they're numbered or not.

ChrisA

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Thread

pylint woes DFS <nospam@dfs.com> - 2016-05-07 12:51 -0400
  Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 03:01 +1000
    Re: pylint woes DFS <nospam@dfs.com> - 2016-05-07 21:16 -0400
      Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 11:36 +1000
        Re: pylint woes DFS <nospam@dfs.com> - 2016-05-07 22:15 -0400
          Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 12:50 +1000
            Re: pylint woes DFS <nospam@dfs.com> - 2016-05-10 18:36 -0400
              Re: pylint woes MRAB <python@mrabarnett.plus.com> - 2016-05-11 02:02 +0100
      Re: pylint woes Stephen Hansen <me+python@ixokai.io> - 2016-05-07 19:14 -0700
        Re: pylint woes DFS <nospam@dfs.com> - 2016-05-07 23:04 -0400
          Re: pylint woes Stephen Hansen <me+python@ixokai.io> - 2016-05-07 20:46 -0700
            Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 10:26 -0400
          Re: pylint woes Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-05-08 08:50 +0300
            Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 10:25 -0400
              Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-09 00:36 +1000
                Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 11:06 -0400
                Re: pylint woes Stephen Hansen <me+python@ixokai.io> - 2016-05-08 08:15 -0700
                Re: pylint woes Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-05-09 13:17 +1200
                Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-09 12:18 +1000
                Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 22:58 -0400
                Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-09 01:15 +1000
                Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 17:06 -0400
              Re: pylint woes Stephen Hansen <me+python@ixokai.io> - 2016-05-08 08:11 -0700
              Re: pylint woes Steven D'Aprano <steve@pearwood.info> - 2016-05-09 01:51 +1000
                Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 17:04 -0400
                Re: pylint woes Steven D'Aprano <steve@pearwood.info> - 2016-05-09 13:09 +1000
      Re: pylint woes MRAB <python@mrabarnett.plus.com> - 2016-05-08 03:21 +0100
      Re: pylint woes Steven D'Aprano <steve@pearwood.info> - 2016-05-08 21:36 +1000
        Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 17:24 -0400
          Re: pylint woes Joel Goldstick <joel.goldstick@gmail.com> - 2016-05-08 17:39 -0400
          Re: pylint woes Steven D'Aprano <steve@pearwood.info> - 2016-05-09 13:46 +1000
  Re: pylint woes Michael Selik <michael.selik@gmail.com> - 2016-05-07 18:42 +0000
  Re: pylint woes Peter Pearson <pkpearson@nowhere.invalid> - 2016-05-07 18:43 +0000
    Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 17:05 -0400
  Re: pylint woes Christopher Reimer <christopher_reimer@icloud.com> - 2016-05-07 11:52 -0700
    Re: pylint woes DFS <nospam@dfs.com> - 2016-05-07 23:38 -0400
      Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 13:56 +1000
      Re: pylint woes Peter Otten <__peter__@web.de> - 2016-05-08 16:19 +0200
  Re: pylint woes Stephen Hansen <me+python@ixokai.io> - 2016-05-07 12:21 -0700
  Re: pylint woes Stephen Hansen <me@ixokai.io> - 2016-05-07 12:23 -0700
  Re: pylint woes Terry Reedy <tjreedy@udel.edu> - 2016-05-07 15:40 -0400
    Re: pylint woes DFS <nospam@dfs.com> - 2016-05-07 23:28 -0400
      Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 13:51 +1000
        Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 00:40 -0400
          Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 14:55 +1000
      Re: pylint woes Stephen Hansen <me+python@ixokai.io> - 2016-05-07 20:55 -0700
      Re: pylint woes Ian Kelly <ian.g.kelly@gmail.com> - 2016-05-07 23:09 -0600
      Re: pylint woes Peter Otten <__peter__@web.de> - 2016-05-08 16:12 +0200
  Re: pylint woes Christopher Reimer <christopher_reimer@icloud.com> - 2016-05-07 12:43 -0700
  Re: pylint woes Ray Cote <rgacote@appropriatesolutions.com> - 2016-05-07 15:52 -0400
  Re: pylint woes Christopher Reimer <christopher_reimer@icloud.com> - 2016-05-07 13:20 -0700
  Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 07:56 +1000
  Re: pylint woes Terry Reedy <tjreedy@udel.edu> - 2016-05-07 21:44 -0400
  Re: pylint woes Steven D'Aprano <steve@pearwood.info> - 2016-05-08 13:25 +1000
    Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 00:10 -0400
      Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 14:21 +1000
      Re: pylint woes "D'Arcy J.M. Cain" <darcy@VybeNetworks.com> - 2016-05-08 08:50 -0400
      Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-08 23:01 +1000
        Re: pylint woes Larry Hudson <orgnut@yahoo.com> - 2016-05-08 13:45 -0700
          Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-09 08:07 +1000
            Re: pylint woes Larry Hudson <orgnut@yahoo.com> - 2016-05-08 18:28 -0700
        Re: pylint woes Dan Sommers <dan@tombstonezero.net> - 2016-05-08 20:49 +0000
          Re: pylint woes Chris Angelico <rosuav@gmail.com> - 2016-05-09 08:10 +1000
      Re: pylint woes Steven D'Aprano <steve@pearwood.info> - 2016-05-09 03:25 +1000
        Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 17:16 -0400
          Re: pylint woes Stephen Hansen <me+python@ixokai.io> - 2016-05-08 14:38 -0700
            Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 17:46 -0400
              Re: pylint woes Stephen Hansen <me+python@ixokai.io> - 2016-05-08 15:05 -0700
                Re: pylint woes DFS <nospam@dfs.com> - 2016-05-08 18:24 -0400

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