On Jun 5, 4:37 am, Ben Finney <ben+pyt...@benfinney.id.au> wrote:
> <jyoun...@kc.rr.com> writes:
> > I was surfing around looking for a way to split a list into equal
> > sections. I came upon this algorithm:
>
> > >>> f = lambda x, n, acc=[]: f(x[n:], n, acc+[(x[:n])]) if x else acc
> > >>> f("Hallo Welt", 3)
> > ['Hal', 'lo ', 'Wel', 't']
>
> > (http://stackoverflow.com/questions/312443/how-do-you-split-a-list-int...)
>
> This is an excellent example of why “clever” code is to be shunned.
> Whoever wrote this needs to spend more time trying to get their code
> past a peer review; the above would be rejected until it was re-written
> to be clear.
>
> Here is my attempt to write the above to be clear (and fixing a couple
> of bugs too):
>
> def split_slices(seq, slicesize, accumulator=None):
> """ Return a list of slices from `seq` each of size `slicesize`.
>
> :param seq: The sequence to split.
> :param slicesize: The maximum size of each slice.
> :param accumulator: A sequence of existing slices to which
> ours should be appended.
> :return: A list of the slices. Each item will be a slice
> from the original `seq` of `slicesize` length; the last
> item may be shorter if there were fewer than `slicesize`
> items remaining.
>
> """
> if accumulator is None:
> accumulator = []
> if seq:
> slice = seq[:slicesize]
> result = split_slices(
> seq[slicesize:], slicesize, accumulator + [slice])
> else:
> result = accumulator
> return result
>
> > It doesn't work with a huge list, but looks like it could be handy in
> > certain circumstances. I'm trying to understand this code, but am
> > totally lost. I know a little bit about lambda, as well as the ternary
> > operator
>
> In Python, ‘lambda’ is merely an alternative syntax for creating
> function objects. The resulting object *is* a function, so I've written
> the above using the ‘def’ syntax for clarity.
>
> The ternary operator is often useful for very simple expressions, but
> quickly becomes too costly to read when the expression is complex. The
> above is one where the writer is so much in love with the ternary
> operator that they have crammed far too much complexity into a single
> expression.
>
> > Just curious if anyone could explain how this works or maybe share a link
> > to a website that might explain this?
>
> Does the above help?
>
> --
> \ “We must find our way to a time when faith, without evidence, |
> `\ disgraces anyone who would claim it.” —Sam Harris, _The End of |
> _o__) Faith_, 2004 |
> Ben Finney
Just my 2p, but isn't the itertools "grouper" recipe prudent?
--
http://mail.python.org/mailman/listinfo/python-list
