CODEWITHSUNDEEP
pythonalgorithmpython-3.x
aryst0krat
aryst0krat

Reputation: 115

Run through a variety of ranges in a list algorithmically

I'm trying to figure out the best way to check a variety of ranges of a list algorithmically and drawing a blank. Here is what the ranges it should check should look like.

#first it checks the whole list, then
foo[1:]
foo[:-1]
foo[2:]
foo[1:-1]
foo[:-2]
foo[3:]
foo[2:-1]
foo[1:-2]
foo[:-3]
#etc, for as long as the ranges will fit in the list

The first and last steps are easy enough - essentially I could just use

foo[iter:]
foo[:-iter]

But the intermediate ones are where I'm not sure how to go about it.

Upvotes: 1

Views: 51

Answers (2)

Jason S
Jason S

Reputation: 13779

This works, although at first glance it is slightly inelegant due to the magic-number ranges.

def decreasing_ranges(seq):
    for length in range(len(seq), 0, -1):
        for start in range(len(seq) - length, -1, -1):
            yield foo[start:start + length]

Upvotes: 1

ranlot
ranlot

Reputation: 656

map(lambda x: foo[x[0]:-x[1]], itertools.permutations(range(1, 4), 2))

Upvotes: 2

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