CODEWITHSUNDEEP
pythonpython-3.xslice
Kitchi
Kitchi

Reputation: 1904

Creating a slice object in python

If I have an array a, I understand how to slice it in various ways. Specifically, to slice from an arbitrary first index to the end of the array I would do a[2:].

But how would I create a slice object to achieve the same thing? The two ways to create slice objects that are documented are slice(start, stop, step) and slice(stop).

So if I pass a single argument like I would in a[2:] the slice object would interpret it as the stopping index rather than the starting index.

Question: How do I pass an index to the slice object with a starting index and get a slice object that slices all the way to the end? I don't know the total size of the list.

Upvotes: 9

Views: 5751

Answers (1)

ShadowRanger
ShadowRanger

Reputation: 155428

Use None everywhere the syntax-based slice uses a blank value:

someseq[slice(2, None)]

is equivalent to:

someseq[2:]

Similarly, someseq[:10:2] can use a preconstructed slice defined with slice(None, 10, 2), etc.

Upvotes: 19

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