Using namedtuples field names for column indices in a list of lists
Tim Chase
python.list at tim.thechases.com
Mon Jan 9 12:08:30 EST 2017
On 2017-01-09 08:31, breamoreboy at gmail.com wrote:
> On Monday, January 9, 2017 at 2:22:19 PM UTC, Tim Chase wrote:
> > I usually wrap the iterable in something like
> >
> > def pairwise(it):
> > prev = next(it)
> > for thing in it:
> > yield prev, thing
> > prev = thing
>
> Or from
> https://docs.python.org/3/library/itertools.html#itertools-recipes:-
>
> def pairwise(iterable):
> "s -> (s0,s1), (s1,s2), (s2, s3), ..."
> a, b = tee(iterable)
> next(b, None)
> return zip(a, b)
>
> This and many other recipes are available in the more-itertools
> module which is on pypi.
Ah, helpful to not have to do it from scratch each time. Also, I see
several others that I've coded up from scratch (particularly the
partition() and first_true() functions).
I usually want to make sure it's tailored for my use cases. The above
pairwise() is my most common use case, but I occasionally want N-wise
pairing
s -> (s0,s1,…sN), (s1,s2,…S{N+1}), (s2,s3,…s{N+2}), …
or to pad them out so either the leader/follower gets *all* of the
values, with subsequent values being a padding value:
# lst = [s0, s1, s2]
(s0,s1), (s1, s2), (s2, PADDING)
# or
(PADDING, s0), (s0, s1), (s1, s2)
but it's good to have my common cases already coded & tested.
-tkc
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