add examples

src/onehot.jl

@@ -39,6 +39,29 @@ adapt_structure(T, xs::OneHotMatrix) = OneHotMatrix(xs.height, adapt(T, xs.data)
   cudaconvert(x::OneHotMatrix{<:CuArray}) = OneHotMatrix(x.height, cudaconvert(x.data))
 end
 
+"""
+    onehot(l, labels[, unk])
+
+Create an [`OneHotVector`](@ref) wtih `l`-th element be `true` based on possible `labels` set.
+If `unk` is given, it retruns `onehot(unk, labels)` if the input label `l` is not find in `labels` or
+it will error.
+
+## Examples
+
+```jldoctest
+julia> onehot(:b, [:a, :b, :c])
+3-element Flux.OneHotVector:
+ false
+  true
+ false
+
+julia> onehot(:c, [:a, :b, :c])
+3-element Flux.OneHotVector:
+ false
+ false
+  true
+```
+"""
 function onehot(l, labels)
   i = something(findfirst(isequal(l), labels), 0)
   i > 0 || error("Value $l is not in labels")
@@ -51,9 +74,49 @@ function onehot(l, labels, unk)
   OneHotVector(i, length(labels))
 end
 
+"""
+    onehotbatch(ls, labels[, unk...])
+
+Create an [`OneHotMatrix`](@ref) with a batch of labels based on possible `labels` set, returns the
+`onehot(unk, labels)` if given labels `ls` is not found in set `labels`.
+
+## Examples
+
+```jldoctest
+julia> onehotbatch([:b, :a, :b], [:a, :b, :c])
+3×3 Flux.OneHotMatrix:
+ false   true  false
+  true  false   true
+ false  false  false
+
+julia> onecold(ans, [:a, :b, :c])
+3-element Array{Symbol,1}:
+  :b
+  :a
+  :b
+```
+"""
 onehotbatch(ls, labels, unk...) =
   OneHotMatrix(length(labels), [onehot(l, labels, unk...) for l in ls])
 
+"""
+    onecold(y[, labels = 1:length(y)])
+
+Inverse operations of [`onehot`](@ref).
+
+## Examples
+
+```jldoctest
+julia> onecold(ans, [:a, :b, :c])
+:c
+
+julia> onecold([true, false, false], [:a, :b, :c])
+:a
+
+julia> onecold([0.3, 0.2, 0.5], [:a, :b, :c])
+:c
+```
+"""
 onecold(y::AbstractVector, labels = 1:length(y)) = labels[Base.argmax(y)]
 
 onecold(y::AbstractMatrix, labels...) =