fix bug - subdataset with zero column

Author: sl-solution

CHANGELOG.md

@@ -1,12 +1,20 @@
 # Dev
 
+## Fixes
+
+* Fix issue with `QuickSortAlg` in future version of Julia
+* Empty the rows of a `SubDataset` without columns
+
+# Version 0.7.12
+
 ## Features
 
 * Users can use `resize!` to resize a data set
 
 ## Fixes
 
 * Fix function signature for some stat functions
+
 # Version 0.7.11
 
 ## Features

src/subdataset/subdataset.jl

@@ -108,7 +108,13 @@ Base.@propagate_inbounds function SubDataset(parent::Dataset, rows::AbstractVect
     @boundscheck if !checkindex(Bool, axes(parent, 1), rows)
         throw(BoundsError(parent, (rows, cols)))
     end
-    SubDataset(parent, SubIndex(index(parent), cols), rows)
+    sindex = SubIndex(index(parent), cols)
+    # SubDataset without columns should not have any row
+    if all(==(0), sindex.remap)
+        SubDataset(parent, sindex, Int[])
+    else
+        SubDataset(parent,sindex , rows)
+    end
 end
 Base.@propagate_inbounds SubDataset(parent::Dataset, ::Colon, cols) =
     SubDataset(parent, axes(parent, 1), cols)

test/subdataset.jl

@@ -297,3 +297,43 @@ end
               SubDataset(sds, [1, 1, 1], :)
     end
 end
+@testset "subdataset with no columns" begin # from DF.jl
+    ds = Dataset(a=1:3, b=4:6)
+    vds = @view ds[[3, 1], 2:1]
+    @test nrow(SubDataset(vds, Int[], :)) == 0
+    @test nrow(SubDataset(vds, Bool[], :)) == 0
+    @test nrow(SubDataset(vds, :, :)) == 0
+    @test nrow(SubDataset(vds, Not(:), :)) == 0
+    @test nrow(SubDataset(vds, Int[], [])) == 0
+    @test nrow(SubDataset(vds, Bool[], [])) == 0
+    @test nrow(SubDataset(vds, :, [])) == 0
+    @test nrow(SubDataset(vds, Not(:), [])) == 0
+    @test_throws BoundsError SubDataset(vds, [1, 2], :)
+
+    @test nrow(view(vds, Int[], :)) == 0
+    @test nrow(view(vds, Bool[], :)) == 0
+    @test nrow(view(vds, :, :)) == 0
+    @test nrow(view(vds, !, :)) == 0
+    @test nrow(view(vds, Not(:), :)) == 0
+    @test nrow(view(vds, Int[], [])) == 0
+    @test nrow(view(vds, Bool[], [])) == 0
+    @test nrow(view(vds, :, [])) == 0
+    @test nrow(view(vds, !, [])) == 0
+    @test nrow(view(vds, Not(:), [])) == 0
+    @test_throws BoundsError view(vds, [1, 2], :)
+
+    @test_throws BoundsError vds[1, 1]
+    @test_throws BoundsError vds[[1, 2], 1]
+
+    @test nrow(getindex(vds, Int[], :)) == 0
+    @test nrow(getindex(vds, Bool[], :)) == 0
+    @test nrow(getindex(vds, :, :)) == 0
+    @test nrow(getindex(vds, !, :)) == 0
+    @test nrow(getindex(vds, Not(:), :)) == 0
+    @test nrow(getindex(vds, Int[], [])) == 0
+    @test nrow(getindex(vds, Bool[], [])) == 0
+    @test nrow(getindex(vds, :, [])) == 0
+    @test nrow(getindex(vds, !, [])) == 0
+    @test nrow(getindex(vds, Not(:), [])) == 0
+    @test_throws BoundsError getindex(vds, [1, 2], :)
+end