Reference · Strings

slice

slice(list | str, int, int=) -> list | str

What it does

The part of a list or a string from a start position up to, but not including, an end position; without an end, up to the end. Positions count from 0; a negative position counts from the end. A string is sliced by characters, and the result is of the same kind as the input: a list gives a list, a string a string.

Examples

print(slice("hello", 1, 3), slice("hello", 2), slice("hello", -3))print(slice([1, 2, 3, 4], 1, 3), slice([1, 2, 3, 4], -2))

el llo llo[2, 3] [3, 4]

Edge cases

• Positions are kept within the value: a start or end past the end is the end, and one before the start is 0, so a slice never fails for being out of range.
• An end before the start gives an empty list or string.
• -1 as the end leaves out the last item; 0, 0 is empty.
• Characters, not bytes: slice("héllo😀", 1, 2) is é, and -1 is the emoji.

print(slice("hello", 0, 100), slice("hello", 10), slice("", 0, 2), slice("abc", -10, 2))print(slice("hello", 3, 1), slice([1, 2, 3, 4], 0, 0))print(slice("hello", -3, -1), slice([1, 2, 3], 1, -1))print(slice("héllo😀", 1, 2), slice("héllo😀", -1))

hello   ab []ll [2]é 😀

Errors

A first argument that is not a list or a string (null included), or a position that is not an int, is a runtime error, not an error value. The start is required.

print(slice(null, 1))

line 1: `slice` expects a list or str, got null

print(slice("abc", "1"))

line 1: `slice` expects an int as argument 2, got str

Chaining

In a pipeline the list or text comes first and the positions follow:

print("hello" | slice(1, 3), [1, 2, 3] | slice(1))let i = index_of("key=value", "=")print(slice("key=value", 0, i), slice("key=value", i + 1))print(range(10) | slice(-3) | map((n) => n * 2))

el [2, 3]key value[14, 16, 18]

See also

take, drop, index_of, len, split, first, last

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