[Baypiggies] How to create a dict of counts using functional programming

David Berthelot david.berthelot at gmail.com
Mon Sep 28 13:19:41 CEST 2015

There's already a function written for that though in the standard library:

On Mon, Sep 28, 2015 at 4:01 AM, Braun Brelin <bbrelin at gmail.com> wrote:

> Hello all,
> I am trying to do the following:
> I have a list that looks like this:
> ['1','2','7','8','8']
> I want to create a dictionary that looks like this:
> {1:1, 2:1,7:1,8:2}
> i.e. the value is the count of the number of times the key appears in
> the list.  The catch is that I'm trying to do this in a functional
> programming way, rather than iteratively.
> I'm trying to use something like map, or reduce or even dict, but I can't
> figure out how to tell
> python to increment the value.  In other words how do I even specify what
> the value is, as it
> seems to be a bit of a chicken and egg scenario.
> I can, for example create a dictionary that sets the values to a constant,
> such as zero using FP,
> but how do I tell it to increment the value for a dictionary that doesn't
> yet exist as I'm in the process of
> building it?
> Thanks,
> Braun Brelin
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