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EllipsisNotation.jl

EllipsisNotation.jl implements 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.

Installation

using Pkg
Pkg.add("EllipsisNotation")
using EllipsisNotation

Example Usage

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

julia> A[.., 1, 2] # Can do as many integers as you want on the end!

For avoiding squeezing dimensions from slicing.

julia> C = ones(3, 3, 3, 3, 3);

julia> size(C[1:1, .., 1:1])
(1, 3, 3, 3, 1)

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

Warning:.. does not work when indexing also with end or begin. For example, A = randn(2,3,4); A[.., 1:end] will not give the intended result. This is a known limitation, and is not likely to be fixed until some necessary changes in the Julia language itself are implemented. See https://github.com/ChrisRackauckas/EllipsisNotation.jl/issues/19 for more details.

Contributing

Acknowledgements

I would like to acknowledge M. Schauer for the .. notation implementation. He had the original idea, I just extended it and put it into a package because of how useful it has been to me.

Reproducibility

The documentation of this SciML package was built using these direct dependencies,
Status `~/_work/EllipsisNotation.jl/EllipsisNotation.jl/docs/Project.toml`
  [e30172f5] Documenter v1.17.0
  [da5c29d0] EllipsisNotation v1.10.0 `~/_work/EllipsisNotation.jl/EllipsisNotation.jl`
and using this machine and Julia version.
Julia Version 1.12.6
Commit 15346901f00 (2026-04-09 19:20 UTC)
Build Info:
  Official https://julialang.org release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 112 × AMD EPYC 7663 56-Core Processor
  WORD_SIZE: 64
  LLVM: libLLVM-18.1.7 (ORCJIT, znver3)
  GC: Built with stock GC
Threads: 1 default, 1 interactive, 1 GC (on 4 virtual cores)
Environment:
  JULIA_CPU_THREADS = 4
  JULIA_NUM_PRECOMPILE_TASKS = 4
A more complete overview of all dependencies and their versions is also provided.
Status `~/_work/EllipsisNotation.jl/EllipsisNotation.jl/docs/Manifest.toml`
  [a4c015fc] ANSIColoredPrinters v0.0.1
  [1520ce14] AbstractTrees v0.4.5
  [944b1d66] CodecZlib v0.7.8
  [ffbed154] DocStringExtensions v0.9.5
  [e30172f5] Documenter v1.17.0
  [da5c29d0] EllipsisNotation v1.10.0 `~/_work/EllipsisNotation.jl/EllipsisNotation.jl`
  [d7ba0133] Git v1.5.0
  [b5f81e59] IOCapture v1.0.0
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  [682c06a0] JSON v1.6.1
  [0e77f7df] LazilyInitializedFields v1.3.0
  [d0879d2d] MarkdownAST v0.1.3
  [69de0a69] Parsers v2.8.6
  [aea7be01] PrecompileTools v1.3.4
  [21216c6a] Preferences v1.5.2
  [2792f1a3] RegistryInstances v0.1.0
  [ec057cc2] StructUtils v2.8.2
  [3bb67fe8] TranscodingStreams v0.11.3
  [2e619515] Expat_jll v2.8.1+0
  [020c3dae] Git_LFS_jll v3.7.1+0
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  [f43a241f] Downloads v1.7.0
  [7b1f6079] FileWatching v1.11.0
  [b77e0a4c] InteractiveUtils v1.11.0
  [ac6e5ff7] JuliaSyntaxHighlighting v1.12.0
  [b27032c2] LibCURL v0.6.4
  [76f85450] LibGit2 v1.11.0
  [8f399da3] Libdl v1.11.0
  [56ddb016] Logging v1.11.0
  [d6f4376e] Markdown v1.11.0
  [ca575930] NetworkOptions v1.3.0
  [44cfe95a] Pkg v1.12.1
  [de0858da] Printf v1.11.0
  [3fa0cd96] REPL v1.11.0
  [9a3f8284] Random v1.11.0
  [ea8e919c] SHA v0.7.0
  [9e88b42a] Serialization v1.11.0
  [6462fe0b] Sockets v1.11.0
  [f489334b] StyledStrings v1.11.0
  [fa267f1f] TOML v1.0.3
  [a4e569a6] Tar v1.10.0
  [8dfed614] Test v1.11.0
  [cf7118a7] UUIDs v1.11.0
  [4ec0a83e] Unicode v1.11.0
  [e66e0078] CompilerSupportLibraries_jll v1.3.0+1
  [deac9b47] LibCURL_jll v8.15.0+0
  [e37daf67] LibGit2_jll v1.9.0+0
  [29816b5a] LibSSH2_jll v1.11.3+1
  [14a3606d] MozillaCACerts_jll v2025.11.4
  [458c3c95] OpenSSL_jll v3.5.4+0
  [efcefdf7] PCRE2_jll v10.44.0+1
  [83775a58] Zlib_jll v1.3.1+2
  [8e850ede] nghttp2_jll v1.64.0+1
  [3f19e933] p7zip_jll v17.7.0+0

You can also download the manifest file and the project file.