[Python-Dev] [Python-checkins] cpython: Add optional *func* argument to itertools.accumulate().

[Georg Brandl]

On 28.03.2011 09:49, Raymond Hettinger wrote:
> 
> On Mar 28, 2011, at 12:38 AM, Daniel Stutzbach wrote:
> 
>> On Sun, Mar 27, 2011 at 10:53 PM, Nick Coghlan <ncoghlan at gmail.com
>> <mailto:ncoghlan at gmail.com>> wrote:
>>
>>     On Mon, Mar 28, 2011 at 2:11 PM, Daniel Stutzbach <stutzbach at google.com
>>     <mailto:stutzbach at google.com>> wrote:
>>     > Is there a good use-case for the func argument?
>>
>>  
>>
>>     The examples that Raymond gives in the docs (cumulative
>>     multiplication, running min/max, cash flow accumulation) look fairly
>>     solid to me.
>>
>>
>> (I had the nagging suspicion that I was making a blunder in my email, but I
>> couldn't see it despite rereading my email several times before sending.  My
>> blunder was in not rereading the patch to see the examples.  Anyway...)
>>
>> When would a running product, min, or max be useful?
> 
> There's no need to speculate.  This API has long been present in other languages
> and libraries.
> 
> Do a google code search for R's builtin functions cumsum, cumprod, cummin, and
> cummax. Look at mumpy's accumulate ufunc which works with many operators. APL
> and K also have an accumulate tool which takes arbitrary functions.

And incidentally I just could have used it myself yesterday.  So thanks for
adding it! :)

Georg