https://github.com/juliadata/invertedindices.jl

A simple index type that allows for inverted selections
https://github.com/juliadata/invertedindices.jl

Last synced: 4 months ago
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A simple index type that allows for inverted selections

• Host: GitHub
• URL: https://github.com/juliadata/invertedindices.jl
• Owner: JuliaData
• License: other
• Created: 2017-02-26T22:49:14.000Z (almost 9 years ago)
• Default Branch: main
• Last Pushed: 2025-08-18T17:53:56.000Z (5 months ago)
• Last Synced: 2025-09-07T16:53:38.552Z (4 months ago)
• Language: Julia
• Size: 55.7 KB
• Stars: 86
• Watchers: 3
• Forks: 9
• Open Issues: 8
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

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README

          
# InvertedIndices

[![Build Status](https://github.com/JuliaData/InvertedIndices.jl/workflows/CI/badge.svg)](https://github.com/JuliaData/InvertedIndices.jl/actions?query=workflow%3ACI+branch%3Amain)

[![Code coverage](https://codecov.io/gh/JuliaData/InvertedIndices.jl/graph/badge.svg?token=D1B9JKlQG5)](https://codecov.io/gh/JuliaData/InvertedIndices.jl)

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

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}

```