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Re: Suggestion: make sequence and map interfaces more similar

Path csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From Terry Reedy <tjreedy@udel.edu>
Newsgroups comp.lang.python
Subject Re: Suggestion: make sequence and map interfaces more similar
Date Thu, 31 Mar 2016 13:41:19 -0400
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On 3/31/2016 10:13 AM, Marko Rauhamaa wrote:

> One could compose a table of correspondences:

with some corrections

>        -------------------------------------------
>        list (L)                    dict (D)
>        -------------------------------------------
>        L[key] = value              D[key] = value
>        del L[key] (*)              del L[key]
>        (*) reassigns all keys
>        key >= 0 and key < len(L)   key in D

'-len(L) <= key < len(L)' or 'key in range(-len(L), len(L)'
Lists, tuples, and ranges have 2 keys for each value,
though that is not guaranteed for sequences in general.

key in D == key in D.keys()

>        range(len(L))               iter(D)

          iter(range(Len(L))          == iter(D.keys())

>        L.clear                     D.clear
>        L.copy                      D.copy
>        lambda key: L[key]          D.get

The purpose of D.get() is to supply a default instead of raising 
KeyError when key not in D. The lambda function above does not do that. 
  Turning subscripting into a function is a side-effect of D.get.  A 
generic get function:

def get(subscriptable, key, default=None):
     try:
         return subscriptable[key]
     except (IndexError, KeyError):
         return default

>        lambda: enumerate(L)        D.items

As I pointed out a couple days ago, an enumerate iterator is quite 
different from a set-like dynamic view.  An actual correspondence:

          enumerate(L)               iter(D.items())

Writing a set-like dynamic view of lists corresponding to D.values() or 
D.items() would be an interesting project.

>        lambda: range(len(L))       D.keys

          iter(range(len(L))          iter(D.keys())
Already given above.  Iterating indexes is now much rarer than iterating 
dict keys.

-- 
Terry Jan Reedy

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Thread

Re: Suggestion: make sequence and map interfaces more similar "Marco S." <mail.python.org@marco.sulla.e4ward.com> - 2016-03-27 20:01 +0200
  Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-28 12:05 +1100
    Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-29 16:08 +0200
    Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-03-30 01:31 +1100
    Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-30 00:29 +0200
    Re: Suggestion: make sequence and map interfaces more similar Terry Reedy <tjreedy@udel.edu> - 2016-03-29 20:55 -0400
    Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-03-30 11:56 +1100
    Re: Suggestion: make sequence and map interfaces more similar Random832 <random832@fastmail.com> - 2016-03-29 23:38 -0400
      Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-03-30 16:43 +1100
        Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-03-30 16:57 +1100
        Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 10:12 +0300
          Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-30 21:17 +1100
            Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 13:28 +0300
              Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-30 12:34 +0200
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 13:57 +0300
              Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-30 23:22 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-30 15:12 +0200
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 02:56 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-30 21:07 +0200
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 13:40 +1100
                Re: Suggestion: make sequence and map interfaces more similar Paul Rubin <no.email@nospam.invalid> - 2016-03-30 19:45 -0700
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-03-31 17:45 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 09:52 +0200
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 21:36 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 12:51 +0200
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 13:22 +0200
                Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-03-31 22:57 +1100
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-31 15:36 +0300
                Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-03-31 23:48 +1100
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-31 17:02 +0300
                Re: Suggestion: make sequence and map interfaces more similar Michael Selik <michael.selik@gmail.com> - 2016-04-01 04:19 -0400
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-31 15:55 +0300
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-31 17:19 +0300
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 15:08 +0200
                Re: Suggestion: make sequence and map interfaces more similar Rustom Mody <rustompmody@gmail.com> - 2016-03-31 06:42 -0700
                Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-04-01 00:11 +1100
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-31 14:17 +0100
                Re: Suggestion: make sequence and map interfaces more similar Random832 <random832@fastmail.com> - 2016-03-31 09:27 -0400
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-31 17:13 +0300
                Re: Suggestion: make sequence and map interfaces more similar Terry Reedy <tjreedy@udel.edu> - 2016-03-31 13:41 -0400
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-31 15:12 +0100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-04-01 09:59 +0200
                Re: Suggestion: make sequence and map interfaces more similar Tim Golden <mail@timgolden.me.uk> - 2016-04-01 09:27 +0100
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-04-01 21:38 +1100
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 13:50 +0300
                Re: Suggestion: make sequence and map interfaces more similar Rustom Mody <rustompmody@gmail.com> - 2016-04-01 07:41 -0700
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-04-01 10:04 +0100
                Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-30 21:35 +0200
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-30 21:31 +0100
            Re: Suggestion: make sequence and map interfaces more similar Manolo Martínez <manolo@austrohungaro.com> - 2016-03-30 12:26 +0200
              Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 13:40 +0300
                Re: Suggestion: make sequence and map interfaces more similar Manolo Martínez <manolo@austrohungaro.com> - 2016-03-30 12:50 +0200
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 14:21 +0300
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-30 14:44 +0300
                Re: Suggestion: make sequence and map interfaces more similar Manolo Martínez <manolo@austrohungaro.com> - 2016-03-30 14:29 +0200
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-30 15:55 +0300
                Re: Suggestion: make sequence and map interfaces more similar Manolo Martínez <manolo@austrohungaro.com> - 2016-03-30 15:13 +0200
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-30 23:27 +1100
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-30 15:48 +0300
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 17:38 +0300
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 17:25 +0300
        Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-30 10:55 +0200
        Re: Suggestion: make sequence and map interfaces more similar Random832 <random832@fastmail.com> - 2016-03-30 08:50 -0400
          Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 03:02 +1100
            Re: Suggestion: make sequence and map interfaces more similar Random832 <random832@fastmail.com> - 2016-03-30 12:52 -0400
              Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 13:44 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 10:04 +0200
                Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-31 13:58 +0200
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-31 13:30 +0100
                Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-31 14:49 +0200
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-31 14:14 +0100
            Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-30 22:00 +0200
            Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-30 21:36 +0100
    Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-30 08:03 +0100

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