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Add showarg(io, ::Slices) printing for eachslice #45355

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5182818
showarg for eachcol etc
mcabbott May 17, 2022
f8a10c0
docstrings
mcabbott May 17, 2022
8068800
whitespace
mcabbott May 18, 2022
b9f7dd8
better handling of empty case
mcabbott May 19, 2022
351e3dc
also hide eltype in compact show
mcabbott May 19, 2022
61b5d8f
comment
mcabbott May 20, 2022
6ff0715
Revert "also hide eltype in compact show"
mcabbott May 31, 2022
eae5a3d
add a 3D example to show dims::Tuple
mcabbott Nov 1, 2022
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115 changes: 90 additions & 25 deletions base/slicearray.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ An `AbstractArray` of slices into a parent array over specified dimension(s),
returning views that select all the data from the other dimension(s).

These should typically be constructed by [`eachslice`](@ref), [`eachcol`](@ref) or
[`eachrow`](@ref).
[`eachrow`](@ref). [`ColumnSlices`](@ref) and [`RowSlices`](@ref) are special cases.

[`parent(s::Slices)`](@ref) will return the parent array.
"""
Expand Down Expand Up @@ -86,9 +86,10 @@ the ordering of the dimensions will match those in `dims`. If `drop = false`, th
`Slices` will have the same dimensionality as the underlying array, with inner
dimensions having size 1.

See [`stack`](@ref)`(slices; dims)` for the inverse of `eachslice(A; dims::Integer)`.
For matrices, the case `dims = 1` is [`eachrow`](@ref), and `dims = 2` is [`eachcol`](@ref).

See also [`eachrow`](@ref), [`eachcol`](@ref), [`mapslices`](@ref) and [`selectdim`](@ref).
[`stack`](@ref)`(slices; dims)` is the inverse of `eachslice(A; dims::Integer, drop=true)`.
See also [`mapslices`](@ref) and [`selectdim`](@ref).

!!! compat "Julia 1.1"
This function requires at least Julia 1.1.
Expand All @@ -106,7 +107,7 @@ julia> m = [1 2 3; 4 5 6; 7 8 9]
7 8 9

julia> s = eachslice(m, dims=1)
3-element RowSlices{Matrix{Int64}, Tuple{Base.OneTo{Int64}}, SubArray{Int64, 1, Matrix{Int64}, Tuple{Int64, Base.Slice{Base.OneTo{Int64}}}, true}}:
3-element eachrow(::Matrix{Int64}) of 3-element slices with eltype Int64:
[1, 2, 3]
[4, 5, 6]
[7, 8, 9]
Expand All @@ -117,11 +118,24 @@ julia> s[1]
2
3

julia> eachslice(m, dims=1, drop=false)
3×1 Slices{Matrix{Int64}, Tuple{Int64, Colon}, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}}, SubArray{Int64, 1, Matrix{Int64}, Tuple{Int64, Base.Slice{Base.OneTo{Int64}}}, true}, 2}:
julia> eachslice(m, dims=1, drop=false) # keyword changes size of container
3×1 eachslice(::Matrix{Int64}, dims = 1, drop = false) of 3-element slices with eltype Int64:
[1, 2, 3]
[4, 5, 6]
[7, 8, 9]

julia> x3 = rand(Int8, 3,4,5);

julia> eachslice(x3, dims=(3,2)) |> summary # order of dims matters here
"5×4 eachslice(::Array{Int8, 3}, dims = (3, 2)) of 3-element slices with eltype Int8"

julia> eachslice(x3, dims=(3,2), drop=false) |> summary
"1×4×5 eachslice(::Array{Int8, 3}, dims = (2, 3), drop = false) of 3-element slices with eltype Int8"

julia> eachslice(Any[pi, 2pi], dims=1) # eachrow would produce vector slices
2-element eachslice(::Vector{Any}, dims = 1) of 0-dimensional slices with eltype Any:
fill(π)
fill(6.283185307179586)
```
"""
@inline function eachslice(A; dims, drop=true)
Expand All @@ -147,20 +161,29 @@ See also [`eachcol`](@ref), [`eachslice`](@ref) and [`mapslices`](@ref).
# Example

```jldoctest
julia> a = [1 2; 3 4]
2×2 Matrix{Int64}:
1 2
3 4
julia> a = [1 2 3; 40 50 60]
2×3 Matrix{Int64}:
1 2 3
40 50 60
Comment on lines -150 to +167
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@mcabbott mcabbott Nov 1, 2022

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Changing these examples from 2x2 to 2x3 will, I hope, make it more obvious which dimension is which.


julia> s = eachrow(a)
2-element RowSlices{Matrix{Int64}, Tuple{Base.OneTo{Int64}}, SubArray{Int64, 1, Matrix{Int64}, Tuple{Int64, Base.Slice{Base.OneTo{Int64}}}, true}}:
[1, 2]
[3, 4]
2-element eachrow(::Matrix{Int64}) of 3-element slices with eltype Int64:
[1, 2, 3]
[40, 50, 60]

julia> s[1]
2-element view(::Matrix{Int64}, 1, :) with eltype Int64:
3-element view(::Matrix{Int64}, 1, :) with eltype Int64:
1
2
3

julia> s isa RowSlices, s[1] isa SubArray
(true, true)
Comment on lines +180 to +181
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@mcabbott mcabbott Nov 1, 2022

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Added because the type alias RowSlices is no longer printed.


julia> eachrow(Any[pi, 2pi]) # reshapes vector to matrix before slicing
2-element eachrow(::Matrix{Any}) of 1-element slices with eltype Any:
[π]
[6.283185307179586]
```
"""
eachrow(A::AbstractMatrix) = _eachslice(A, (1,), true)
Expand All @@ -185,20 +208,31 @@ See also [`eachrow`](@ref), [`eachslice`](@ref) and [`mapslices`](@ref).
# Example

```jldoctest
julia> a = [1 2; 3 4]
2×2 Matrix{Int64}:
1 2
3 4
julia> a = [1 2 3; 40 50 60]
2×3 Matrix{Int64}:
1 2 3
40 50 60

julia> s = eachcol(a)
2-element ColumnSlices{Matrix{Int64}, Tuple{Base.OneTo{Int64}}, SubArray{Int64, 1, Matrix{Int64}, Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}, true}}:
[1, 3]
[2, 4]
3-element eachcol(::Matrix{Int64}) of 2-element slices with eltype Int64:
[1, 40]
[2, 50]
[3, 60]

julia> s[1]
2-element view(::Matrix{Int64}, :, 1) with eltype Int64:
1
3
julia> s[3]
2-element view(::Matrix{Int64}, :, 3) with eltype Int64:
3
60

julia> s isa ColumnSlices
true

julia> parent(s) === a
true

julia> eachcol('a':'c') # accepts AbstractVector too, reshapes to 1-colum matrix:
1-element eachcol(reshape(::StepRange{Char, Int64}, 3, 1)) of 3-element slices with eltype Char:
['a', 'b', 'c']
```
"""
eachcol(A::AbstractMatrix) = _eachslice(A, (2,), true)
Expand Down Expand Up @@ -243,3 +277,34 @@ end
end

parent(s::Slices) = s.parent

function _element_size(s::Slices)
long = map((n,l) -> l === (:) ? n : nothing, size(s.parent), s.slicemap)
filter(!isnothing, long)
end

# These control summary printing, like `3-element eachcol(adjoint(::Matrix{Int64})) of ...`
function showarg(io::IO, s::ColumnSlices, toplevel)
print(io, "eachcol(")
showarg(io, parent(s), false)
print(io, ')')
toplevel && print(io, " of ", dims2string(_element_size(s)), " slices with eltype ", eltype(eltype(s)))
return nothing
end
function showarg(io::IO, s::RowSlices, toplevel)
print(io, "eachrow(")
showarg(io, parent(s), false)
print(io, ')')
toplevel && print(io, " of ", dims2string(_element_size(s)), " slices with eltype ", eltype(eltype(s)))
return nothing
end
function showarg(io::IO, s::Slices, toplevel)
drop = ndims(s) + ndims(eltype(s)) > ndims(parent(s))
dims_vec = filter(c -> c isa Integer, [findfirst(==(d), s.slicemap) for d in 1:ndims(parent(s))])
dims = length(dims_vec) == 1 ? only(dims_vec) : Tuple(dims_vec)
print(io, "eachslice(")
showarg(io, parent(s), false)
print(io, ", dims = ", dims, drop ? ", drop = false)" : ")")
toplevel && print(io, " of ", dims2string(_element_size(s)), " slices with eltype ", eltype(eltype(s)))
return nothing
end