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parentindexes

parentindexes(A)

From an array view A, returns the corresponding indexes in the parent

Examples

In the Julia programming language, the function parentindexes(A) returns the corresponding indexes in the parent array view A.

julia> A = reshape([1, 2, 3, 4, 5, 6], (2, 3))
2×3 reshape(::Vector{Int64}, 2, 3) with eltype Int64:
 1  3  5
 2  4  6

julia> parentindexes(A)
6-element Array{CartesianIndex{2},1}:
 CartesianIndex(1, 1)
 CartesianIndex(2, 1)
 CartesianIndex(1, 2)
 CartesianIndex(2, 2)
 CartesianIndex(1, 3)
 CartesianIndex(2, 3)

Here are some common examples of its use:

1. Obtain parent indexes from a reshaped array:

   julia> A = reshape([1, 2, 3, 4, 5, 6], (2, 3));
   julia> parentindexes(A)
   6-element Array{CartesianIndex{2},1}:
   CartesianIndex(1, 1)
   CartesianIndex(2, 1)
   CartesianIndex(1, 2)
   CartesianIndex(2, 2)
   CartesianIndex(1, 3)
   CartesianIndex(2, 3)

   This example shows how to retrieve the parent indexes from a reshaped array A.

2. Get parent indexes from a subarray view:

   julia> A = [1 2 3; 4 5 6; 7 8 9];
   julia> B = view(A, 2:3, 1:2);
   julia> parentindexes(B)
   6-element Array{CartesianIndex{2},1}:
   CartesianIndex(2, 1)
   CartesianIndex(3, 1)
   CartesianIndex(2, 2)
   CartesianIndex(3, 2)

   In this example, the parentindexes function is used to obtain the parent indexes from a subarray view B.

Note: The CartesianIndex type represents a multi-dimensional index.

If the array view A is not provided or is empty, the parentindexes function will return an empty array.

See Also

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