List.Positions

List

Returns a list of zero-based index positions for all elements in the given list.

Syntax

List.Positions(list as list) as list

Parameters

Name	Type	Required	Description
`list`	`list`	Yes	The list whose positions are to be returned.

Return Value

list — A list of integers {0, 1, 2, ...} with one entry per element in the source list.

Remarks

List.Positions returns a list of zero-based integer indices, one for each element in the input list. For a list of length N, it returns {0, 1, 2, ..., N-1}. It is equivalent to List.Numbers(0, List.Count(list)).

The primary use case is enabling index-aware iteration: by combining the positions list with the original list using List.Zip, you get {{0, item0}, {1, item1}, ...} pairs that let you know each item's position during a transform. This is the standard M pattern for "transform with index" — something that has no built-in direct syntax.

For an empty list, returns an empty list {}. The result is always consecutive integers starting at 0. If you need indices starting at 1, use List.Transform(List.Positions(list), each _ + 1) or List.Numbers(1, List.Count(list)).

Examples

Example 1: Get positions of a list

List.Positions({"A", "B", "C", "D"})

Result

	Result
1	{0, 1, 2, 3}

Example 2: Pair each item with its index using List.Zip

let
    Items = {"Alpha", "Beta", "Gamma"},
    Indexed = List.Zip({List.Positions(Items), Items})
in
    Indexed

Applied Steps

The final output — a list of {position, item} pairs for each element in Items.

	Result
1	{{0, Alpha}, {1, Beta}, {2, Gamma}}

Example 3: Filter items by even index positions

let
    Items = {"A", "B", "C", "D", "E", "F"},
    Positions = List.Positions(Items),
    EvenIndexItems = List.Transform(
        List.Select(Positions, each Number.Mod(_, 2) = 0),
        each Items{_}
    )
in
    EvenIndexItems