InvertedIndices.jl

A simple index type that allows for inverted selections
Author mbauman
Popularity
32 Stars
Updated Last
3 Months Ago
Started In
February 2017

InvertedIndices

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This very small package just exports one type: the InvertedIndex, or Not for short. It can wrap any supported index type and may be used as an index into any AbstractArray subtype, including OffsetArrays.

Upon indexing into an array, the InvertedIndex behaves like a 1-dimensional collection of the indices of the array that are not in the index it wraps. Bounds are checked to ensure that the excluded index is within the bounds of the array — even though it is skipped. The InvertedIndex behaves like a 1-dimensional collection of its inverted indices. If the excluded index spans multiple dimensions (like a multidimensional logical mask or CartesianIndex), then the inverted index will similarly span multiple dimensions.

julia> using InvertedIndices

help?> InvertedIndex
search: InvertedIndex InvertedIndices

  InvertedIndex(idx)
  Not(idx)

  Construct an inverted index, selecting all indices not in the passed idx.

  ...

julia> A = reshape(1:12, 3, 4)
3×4 Base.ReshapedArray{Int64,2,UnitRange{Int64},Tuple{}}:
 1  4  7  10
 2  5  8  11
 3  6  9  12

julia> A[Not(2), Not(2:3)]
2×2 Array{Int64,2}:
 1  10
 3  12

julia> A[Not(iseven.(A))]
6-element Array{Int64,1}:
  1
  3
  5
  7
  9
 11

julia> A[Not(:)]
0-element Array{Int64,1}

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