On Feb 17, 4:03 pm, Boris Borcic <[EMAIL PROTECTED]> wrote:
> George Sakkis wrote:
> > On Feb 17, 7:51 am, Arnaud Delobelle <[EMAIL PROTECTED]> wrote:
>
> >> BTW, I keep using the idiom itertools.chain(*iterable). I guess that
> >> during function calls *iterable gets expanded to a tuple. Wouldn't it
> >> be nice to have an equivalent one-argument function that takes an
> >> iterable of iterables and return the 'flattened' iterable?
>
> > Indeed; I don't have any exact numbers but I roughly use this idiom as
> > often or more as the case where chain() takes a known fixed number of
> > arguments. The equivalent function you describe is trivial:
>
> > def chain2(iter_of_iters):
> > for iterable in iter_of_iters:
> > for i in iterable:
> > yield i
>
> or fwiw
>
> chainstar = lambda iters : (x for it in iters for x in it)
>
> - a form that better suggests how to inline it in the calling expression, if
> applicable.
Indeed:
def flattendict(d):
def gen(d, pfx=()):
return (x for k, v in d.iteritems()
for x in (gen(v, pfx+(k,)) if isinstance(v, dict)
else ((pfx+(k,), v),)))
return dict(gen(d))
I don't know, I find the chain(*...) version more readable, although
this one is probably better. Please, Mr itertools, can we have
chainstar?
--
Arnaud
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