Re: why python don't support "extended slice direct assignment" for lists?
On Fri, Jul 2, 2010 at 7:19 PM, Robert William Hanks wrote: > to say is "wrong" i think is a bit too much, its just a different type of > usage, this type of sintax is extensively used in numpy arrays (extended > slice came from numerical python), just asking why not extend the sintax to > python list. (not sure if you can use None as in the code i posted in numpy > but numbers are ok). I was just rewriting some numpy code in pure python (no > numpy for python3 yet), personally i think the pure python way is just ugly > and more expensive. > > On Fri, Jul 2, 2010 at 10:55 PM, wrote: >> >> Send Python-list mailing list submissions to >> python-l...@python.org >> >> To subscribe or unsubscribe via the World Wide Web, visit >> http://mail.python.org/mailman/listinfo/python-list >> or, via email, send a message with subject or body 'help' to >> python-list-requ...@python.org >> >> You can reach the person managing the list at >> python-list-ow...@python.org >> >> When replying, please edit your Subject line so it is more specific >> than "Re: Contents of Python-list digest..." >> >> Today's Topics: Please avoid replying to the list digest, especially without trimming, as it adds noise to the conversation (and can screw up threading). Cheers, Chris -- http://mail.python.org/mailman/listinfo/python-list
Re: why python don't support "extended slice direct assignment" for lists?
to say is "wrong" i think is a bit too much, its just a different type of
usage, this type of sintax is extensively used in numpy arrays (extended
slice came from numerical python), just asking why not extend the sintax to
python list. (not sure if you can use None as in the code i posted in numpy
but numbers are ok). I was just rewriting some numpy code in pure python (no
numpy for python3 yet), personally i think the pure python way is just ugly
and more expensive.
On Fri, Jul 2, 2010 at 10:55 PM, wrote:
> Send Python-list mailing list submissions to
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> or, via email, send a message with subject or body 'help' to
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> When replying, please edit your Subject line so it is more specific
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> Today's Topics:
>
> 1. Re: Why defaultdict? (Steven D'Aprano)
> 2. Re: why python don't support "extended slice direct
> assignment" for lists? (Shashwat Anand)
> 3. Sorting dicts inside dicts (abhijeet thatte)
> 4. Re: The real problem with Python 3 - no business case for
> conversion (was "I strongly dislike Python 3") (Shashwat Anand)
> 5. Crash in PyThread_acquire_lock (moerchendiser2k3)
> 6. Re: why python don't support "extended slice direct
> assignment" for lists? (MRAB)
> 7. Re: Sorting dicts inside dicts (MRAB)
> 8. Re: tp_richcompare vs tp_compare (Aahz)
> 9. Re: The real problem with Python 3 - no business case for
> conversion(was "I strongly dislike Python 3") (Aahz)
> 10. Re: Anyone using GPG or PGP encryption/signatures in your
> Python apps? (Martin Manns)
>
>
> -- Forwarded message --
> From: Steven D'Aprano
> To: python-list@python.org
> Date: 02 Jul 2010 23:59:52 GMT
> Subject: Re: Why defaultdict?
> On Fri, 02 Jul 2010 04:11:49 +, Steven D'Aprano wrote:
>
> > I would like to better understand some of the design choices made in
> > collections.defaultdict.
> [...]
>
>
> Thanks to all who replied.
>
>
> --
> Steven
>
>
>
>
>
> -- Forwarded message --
> From: Shashwat Anand
> To: Robert William Hanks
> Date: Sat, 3 Jul 2010 05:32:31 +0530
> Subject: Re: why python don't support "extended slice direct assignment"
> for lists?
>
>
> On Sat, Jul 3, 2010 at 4:54 AM, Robert William Hanks <
> astroultra...@gmail.com> wrote:
>
>> why pure python don't support "extended slice direct assignment" for
>> lists?
>>
>> today we have to write like this,
>>
>> >>> aList=[0,1,2,3,4,5,6,7,8,9]
>> >>> aList
>> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>> >>> aList[::2]= [None]*len(aList[::2]) #or do the math by hand, what's
>> not always possible
>>
>
> Can you show me a case where it really is cumbersome.
>
>
>> >>> aList
>> [None, 1, None, 3, None, 5, None, 7, None, 9]
>>
>> why not accept syntax like this for extended slice
>>
>> aList[::2] = None
>>
>> when let's say, the left side is a list and the right side is bool, int or
>> float.
>> the laborious [nunber]*len(aList[::2]) seens to me less readable when you
>> want to set lost of items of a list to the same number.
>> Also correct me if i am wrong, calling len() and building a list to this
>> kind of operation seems a waste.
>>
>
> >>> aList[::2]
> [0, 2, 4, 6, 8]
> Which means you are doing [0, 2, 4, 6, 8] = None, which is plain and simple
> - wrong. How will you define the legitimacy of this statement.
> What you are basically doing here is,,
>
> >>> [None]*len(aList[::2])
> [None, None, None, None, None]
> >>> aList[::2]
> [0, 2, 4, 6, 8]
>
> Setting [0, 2, 4, 6, 8] to [None, None, None, None, None], thereby
> operating on two similar data structure (here list)
>
>
>> Just want some feedback.
>>
>
> Just my thoughts.
>
> ~l0nwlf
>
>
>
> -- Forwarded message --
> From: abhijeet thatte
> To: python-list@python.org
> Date: Fri, 2 Jul 2010 17:17:36 -0700
> Subject: Sorting dicts inside dicts
> Hi,
> I have a huge dict structure like below:
> *
> {'module':{'reg_dict_0':{'name':'abc','reg_addr':'2004'},
Re: why python don't support "extended slice direct assignment" for lists?
Robert William Hanks wrote: why pure python don't support "extended slice direct assignment" for lists? today we have to write like this, >>> aList=[0,1,2,3,4,5,6,7,8,9] >>> aList [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> aList[::2]= [None]*len(aList[::2]) #or do the math by hand, what's not always possible >>> aList [None, 1, None, 3, None, 5, None, 7, None, 9] why not accept syntax like this for extended slice aList[::2] = None when let's say, the left side is a list and the right side is bool, int or float. the laborious [nunber]*len(aList[::2]) seens to me less readable when you want to set lost of items of a list to the same number. Also correct me if i am wrong, calling len() and building a list to this kind of operation seems a waste. Just want some feedback. When you're assigning to a list slice, why should it duplicate an int but not a list? Or in general, duplicate something that's not iterable but not something that is iterable? A string is iterable, so what should: >>> a[ : : 2] = "abcde" do? It's just simpler and less surprising the way it is. -- http://mail.python.org/mailman/listinfo/python-list
Re: why python don't support "extended slice direct assignment" for lists?
On Sat, Jul 3, 2010 at 4:54 AM, Robert William Hanks < astroultra...@gmail.com> wrote: > why pure python don't support "extended slice direct assignment" for lists? > > today we have to write like this, > > >>> aList=[0,1,2,3,4,5,6,7,8,9] > >>> aList > [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] > >>> aList[::2]= [None]*len(aList[::2]) #or do the math by hand, what's not > always possible > Can you show me a case where it really is cumbersome. > >>> aList > [None, 1, None, 3, None, 5, None, 7, None, 9] > > why not accept syntax like this for extended slice > > aList[::2] = None > > when let's say, the left side is a list and the right side is bool, int or > float. > the laborious [nunber]*len(aList[::2]) seens to me less readable when you > want to set lost of items of a list to the same number. > Also correct me if i am wrong, calling len() and building a list to this > kind of operation seems a waste. > >>> aList[::2] [0, 2, 4, 6, 8] Which means you are doing [0, 2, 4, 6, 8] = None, which is plain and simple - wrong. How will you define the legitimacy of this statement. What you are basically doing here is,, >>> [None]*len(aList[::2]) [None, None, None, None, None] >>> aList[::2] [0, 2, 4, 6, 8] Setting [0, 2, 4, 6, 8] to [None, None, None, None, None], thereby operating on two similar data structure (here list) > Just want some feedback. > Just my thoughts. ~l0nwlf -- http://mail.python.org/mailman/listinfo/python-list
