JuliaLang/julia

Ellipsis slicing

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#5,405 opened on Jan 15, 2014

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 (29 comments) (8 reactions) (0 assignees)Julia (5,773 forks)batch import
arrayshelp wantedparser

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Description

Numpy has this ellipsis notation for filling index tuples up to dimension, where in A[..., i, k] ... is interpreted as shorthand for the number of colons :, :, : etc needed to fill the indexing tuple up to dimension n.

http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html

This gives nice access to contiguous subarrays in the dense array case and would be not more harmful than the : notation itself.

Was this feature already considered? It was mentioned by @toivoh on the mailing list, but did not trigger discussion.

Contributor guide

Research direction
Study the current array indexing implementation in Julia's parser and AST. Understand how colons are used in indexing and modify the parser to recognize '...' as a placeholder for multiple colons. Ensure that the feature is compatible with the existing syntax and that it correctly expands based on the dimensionality of the array. Test with various array shapes and indexing scenarios.
Tech stack
None
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30