docstring comment about eachslice

JuliaLang · Feb 9, 2022 · 4ce40cc · 4ce40cc
1 parent 16aca24
commit 4ce40cc
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diff --git a/base/abstractarray.jl b/base/abstractarray.jl
@@ -2770,6 +2770,11 @@ julia> map(g, eachslice(A, dims=2))
 julia> mapslices(sum, A; dims=(1,3)) == sum(A; dims=(1,3))
 true
 ```
+
+Notice that in `eachslice(A; dims=2)`, the specified dimension is the
+one *without* a colon in the slice. This is `view(A,:,i,:)`, whereas
+`mapslices(f, A; dims=(1,3))` uses `A[:,i,:]`. The function `f` may mutate
+values in the slice without affecting `A`.
 """
 function mapslices(f, A::AbstractArray; dims)
     isempty(dims) && return map(f, A)