API

Implementation of the notation .. for indexing arrays. It's similar to the Python ... in that it means 'all the columns before (or after)'.

.. slurps dimensions greedily, meaning that the first occurrence of .. in an index expression creates as many slices as possible. Other instances of .. afterward are treated simply as slices. Usually, you should only use one instance of .. in an indexing expression to avoid possible confusion.

Example

julia> using EllipsisNotation

julia> A = Array{Int}(undef, 2, 4, 2);

julia> A[.., 1] = [2 1 4 5
                   2 2 3 6];

julia> A[.., 2] = [3 2 6 5
                   3 2 6 6];

julia> A[:, :, 1] == [2 1 4 5
                      2 2 3 6]
true

julia> A[1, ..] = reshape([3 4
                           5 6
                           4 5
                           6 7], 1, 4, 2); # drops singleton dimension

julia> B = [3 4
            5 6
            4 5
            6 7];

julia> B == reshape(A[1, ..], 4, 2)
true

Ellipsis

The singleton type of ... Packages that add .. support to their own array or indexing machinery dispatch on this type, so it is part of the public API even though the value .. is the only instance ever constructed.