[Python-ideas] grouping / dict of lists

[Chris Barker]

On Mon, Jul 2, 2018 at 11:50 PM, Chris Barker <chris.barker at noaa.gov> wrote:

> - keep the key function optional parameter.
> - add a value function optional parameter. -- it really makes any case
> where you don't want to store the whole item a lot easier.
>
> - Have the default key function be itemgetter(0) and the default value
> function be itemgetter(1) (or some similar way to implement default support
> for processing an iterable of (key, value) pairs.
>
> Having no value function and an equality default for the key function may
> be "common", but it's also pretty much useless -- why have a useless
> default?
>
> Thinking this through now I do see that having key and value default to to
> the pair method means that if you specify  key function, you will probably
> have to specify a value function as well -- so maybe that's not ideal.
>

OK, I prototyped a class solution that defaults to key, value pairs, but
you can specify a key and/or value function. and with convoluted logic, if
you specify just a key, then the value defaults to the entire item. So
folks will pretty much get what they expect.

I think it's actually pretty slick -- best of both worlds?

Code here:

https://github.com/PythonCHB/grouper/blob/master/grouper/grouper.py

-CHB


-- 

Christopher Barker, Ph.D.
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Chris.Barker at noaa.gov
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