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findnz/nnz mismatch: findnz returns actual, not structural zeros #23121

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StefanKarpinski opened this issue Aug 3, 2017 · 1 comment
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findnz/nnz mismatch: findnz returns actual, not structural zeros #23121

StefanKarpinski opened this issue Aug 3, 2017 · 1 comment
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@andreasnoack
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domain:arrays:sparse Sparse arrays domain:linear algebra Linear algebra stdlib Julia's standard library
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0.7

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@StefanKarpinski
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julia> S = sparse([1], [1], [0])
1×1 SparseMatrixCSC{Int64,Int64} with 1 stored entry:
  [1, 1]  =  0

julia> nnz(S)
1

julia> findnz(S)
(Int64[], Int64[], Int64[])

julia> findn(S)
(Int64[], Int64[])

Given their similar naming, it seems like these should match. Given the decision in #23005 that we're replacing countnz(S) with count(!iszero, S) it might make sense to find actual non-zeros with a more generic function and a !iszero predicate.
@StefanKarpinski StefanKarpinski added this to the 1.0 milestone Aug 3, 2017
@StefanKarpinski StefanKarpinski added the stdlib Julia's standard library label Nov 20, 2017
andreasnoack added a commit that referenced this issue Nov 23, 2017
@andreasnoack
Make findn and findnz behavior match nnz such that length of returned
50a9e65 
vectors is nnz.

Fixes #23121
@andreasnoack andreasnoack mentioned this issue Nov 23, 2017
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@KristofferC
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#24724

andreasnoack added a commit that referenced this issue Nov 29, 2017
@andreasnoack
Make findn and findnz behavior match nnz such that length of returned (…
0335175 
…#24724)

vectors is nnz.

Fixes #23121
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@StefanKarpinski @andreasnoack @KristofferC