Steven D'Aprano wrote:
> I have a colleague who is allergic to mutating data structures. Yeah, I
> know, he needs to just HTFU but I thought I'd humour him.
>
> Suppose I have an iterator that yields named tuples:
>
> Parrot(colour='blue', species='Norwegian', status='tired and shagged out')
>
> and I want to collect them by colour:
>
> accumulator = {'blue': [], 'green': [], 'red': []}
> for parrot in parrots:
> accumulator[parrot.colour].append(parrot)
>
>
> That's pretty compact and understandable, but it require mutating a bunch
> of pre-allocated lists inside an accumulator. Can we re-write this in a
> functional style?
>
> The obvious answer is "put it inside a function, then pretend it works by
> magic" but my colleague's reply to that is "Yes, but I'll know that its
> actually doing mutation inside the function".
>
>
> Help me humour my colleague.
Wouldn't it be on your colleague to provide a competetive "functional"
version?
However, reusing Gregory's sample data:
>>> def color(p): return p.color
...
>>> {c: list(ps) for c, ps in groupby(
... sorted(parrot_generator(), key=color), key=color)}
{'red': [Hawaiian/red/laid back], 'blue': [Norwegian/blue/tired and shagged
out, Norwegian/blue/dead, French/blue/tres bon], 'green':
[Portugese/green/perky, Italian/green/excited]}
--
https://mail.python.org/mailman/listinfo/python-list
