Add method Base.diff(nda::NamedDimsArray; dims) closes #195 (#209)

* Add method `Base.diff(nda::NamedDimsArray; dims)`

* Revert "Add method `Base.diff(nda::NamedDimsArray; dims)`"

This reverts commit 651afca.

* Add method `Base.diff(nda::NamedDimsArray; dims)`

* Remove extra empty line in test/functions_math.jl

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Avoid using unname() in diff() test in test/functions_math.jl

Co-authored-by: Glenn Moynihan <glenn.moynihan@invenialabs.co.uk>

* Bump version to 1.2.0

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Glenn Moynihan <glenn.moynihan@invenialabs.co.uk>

Project.toml

@@ -1,7 +1,7 @@
 name = "NamedDims"
 uuid = "356022a1-0364-5f58-8944-0da4b18d706f"
 authors = ["Invenia Technical Computing Corporation"]
-version = "1.1.0"
+version = "1.2.0"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/functions_math.jl

@@ -120,6 +120,11 @@ function Base.inv(nda::NamedDimsArray{L,T,2}) where {L,T}
     return NamedDimsArray{names}(data)
 end
 
+function Base.diff(nda::NamedDimsArray{L}; dims) where {L}
+    data = diff(parent(nda); dims=dim(L, dims))
+    return NamedDimsArray{L}(data)
+end
+
 # Statistics
 for fun in (:cor, :cov)
     @eval function Statistics.$fun(a::NamedDimsArray{L,T,2}; dims=1, kwargs...) where {L,T}

test/functions_math.jl

@@ -208,6 +208,13 @@ end
     @test inv(nda) * nda ≈ NamedDimsArray{(:b, :b)}([1.0 0; 0 1])
 end
 
+@testset "diff" begin
+    arr = [1.0 2; 3 4]
+    nda = NamedDimsArray{(:a, :b)}(arr)
+    @test diff(nda; dims=:a) == diff(arr; dims=1)
+    @test typeof(diff(nda; dims=:a)) == typeof(nda)
+    @test diff(nda; dims=:b) == diff(nda; dims=2)
+end
 
 @testset "cov/cor" begin
     @testset "symmetric_names" begin