# Indexing SparseMatrixCSC using CartesianIndices

**URL:** <https://discourse.julialang.org/t/indexing-sparsematrixcsc-using-cartesianindices/36631>\
**Category:** General Usage\
**Tags:** question, indexing\
**Created:** [March 28, 2020, 7:19am UTC](https://discourse.julialang.org/t/indexing-sparsematrixcsc-using-cartesianindices/36631 "2020-03-28T07:19:07Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jlchan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jlchan/32/10958_2.png) [@jlchan](https://discourse.julialang.org/u/jlchan)\
**Post date:** [March 28, 2020, 7:19am UTC](https://discourse.julialang.org/t/indexing-sparsematrixcsc-using-cartesianindices/36631/1 "2020-03-28T07:19:07Z")

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I’m having trouble indexing into SparseArrays using CartesianIndices (plural). The following Julia-1.4 code

```julia
using SparseArrays
A = sparse(randn(4,4))
A[CartesianIndices((1:2,1:2))]

```

gives `ERROR: MethodError: no method matching isless(::CartesianIndex{2}, ::Int64)`…

As far as I can tell, this was fixed for a single CartesianIndex in [this PR](https://github.com/JuliaLang/julia/pull/33225) and [this PR](https://github.com/JuliaLang/julia/issues/30981), but doesn’t extend to CartesianIndices. Was this on purpose?

Also, etiquette-wise, should I be asking these questions on the PR threads instead of Discourse?

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<div class="post-metadata">

**Author:** ![mauro3](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mauro3/32/292_2.png) [@mauro3](https://discourse.julialang.org/u/mauro3)\
**Post date:** [March 28, 2020, 7:50am UTC](https://discourse.julialang.org/t/indexing-sparsematrixcsc-using-cartesianindices/36631/2 "2020-03-28T07:50:57Z")

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This is a bug, you should report it (if it hasn’t been reported yet).

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<div class="post-metadata">

**Author:** ![jlchan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jlchan/32/10958_2.png) [@jlchan](https://discourse.julialang.org/u/jlchan)\
**Post date:** [March 28, 2020, 7:56am UTC](https://discourse.julialang.org/t/indexing-sparsematrixcsc-using-cartesianindices/36631/3 "2020-03-28T07:56:43Z")

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Thanks! Will do