CODEWITHSUNDEEP
pythonlistsyntaxfor-loop
roamcel
roamcel

Reputation: 645

Python list return statement deciphering

I have the following statement in a python routine:

return [hulls[h][i] for h, i in hull]

And I can't figure out what it does actually return.

I mean, hulls is a list of hull, so 'hulls[n]' is of type 'hull'. Additionally, hull is of type 'Point' hull is a list of points, but

for h, i in hull?

The docs don't mention why and how you can perform such a call, and it smells like some sort of list comprehension call, but I still can't read that syntax properly.

So I'd like help in understanding how you can translate the sentence in pseudocode, or c#

Thanks a lot.

Upvotes: 0

Views: 229

Answers (3)

rakoonise
rakoonise

Reputation: 539

Yes, David is correct. If you're still confused about the line for h, i in hull: I think it means that hull is a list of tuples that have multiple elements. So you're using every element in hull to use as indices for hulls.

Upvotes: 0

canard
canard

Reputation: 11

Hulls looks to be a two dimensional array of things. Hull is a list of pairs of ints (x,y). For each coordinate in Hull, it returns the item in hulls in that place.

Upvotes: 1

David Alber
David Alber

Reputation: 18111

Yes, it is list comprehension. Your return statement could be rewritten less compactly as:

result = []
for h, i in hull:
    result.append(hulls[h][i])
return result

Upvotes: 3

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