Merge pull request #1888 from TLipede/speed-onehot

Author: darsnack

src/onehot.jl

@@ -183,9 +183,24 @@ julia> reshape(1:15, 3, 5) * oh  # this matrix multiplication is done efficientl
  3  6  15  3  9  3  12  3  6  15  3
 ```
 """
-onehotbatch(ls, labels, default...) = _onehotbatch(ls, length(labels) < 32 ? Tuple(labels) : labels, default...)
-# NB function barier:
-_onehotbatch(ls, labels, default...) = batch([onehot(l, labels, default...) for l in ls])
+onehotbatch(data, labels, default...) = _onehotbatch(data, length(labels) < 32 ? Tuple(labels) : labels, default...)
+
+function _onehotbatch(data, labels)
+  indices = UInt32[something(_findval(i, labels), 0) for i in data]
+  if 0 in indices
+    for x in data
+      isnothing(_findval(x, labels)) && error("Value $x not found in labels")
+    end
+  end
+  return OneHotArray(indices, length(labels))
+end
+
+function _onehotbatch(data, labels, default)
+  default_index = _findval(default, labels)
+  isnothing(default_index) && error("Default value $default is not in labels")
+  indices = UInt32[something(_findval(i, labels), default_index) for i in data]
+  return OneHotArray(indices, length(labels))
+end
 
 """
     onecold(y::AbstractArray, labels = 1:size(y,1))

test/onehot.jl

@@ -18,6 +18,8 @@ using Test
   @test onehotbatch("abc", 'a':'c') == Bool[1 0 0; 0 1 0; 0 0 1]
   @test onehotbatch("zbc", ('a', 'b', 'c'), 'a') == Bool[1 0 0; 0 1 0; 0 0 1]
 
+  @test onehotbatch([10, 20], [30, 40, 50], 30) == Bool[1 1; 0 0; 0 0]
+
   @test_throws Exception onehotbatch([:a, :d], [:a, :b, :c])
   @test_throws Exception onehotbatch([:a, :d], (:a, :b, :c))
   @test_throws Exception onehotbatch([:a, :d], [:a, :b, :c], :e)