add datatype to OneHotEncoder and ContinuousEncoder

src/builtins/Transformers.jl

@@ -732,6 +732,7 @@ end
     drop_last::Bool            = false
     ordered_factor::Bool       = true
     ignore::Bool               = false
+    datatype::DataType         = Float64  
 end
 
 # we store the categorical refs for each feature to be encoded and the
@@ -874,7 +875,7 @@ function MMI.transform(transformer::OneHotEncoder, fitresult, X)
             names = last.(pairs)
             cols_to_add = map(refs) do ref
                 if ismissing(ref) missing
-                else float.(hot(col, ref))
+                else transformer.datatype.(hot(col, ref))
                 end
             end
             append!(new_cols, cols_to_add)
@@ -893,6 +894,7 @@ end
 @with_kw_noshow mutable struct ContinuousEncoder <: Unsupervised
     drop_last::Bool                = false
     one_hot_ordered_factors::Bool  = false
+    datatype::DataType             = Float64
 end
 
 function MMI.fit(transformer::ContinuousEncoder, verbosity::Int, X)
@@ -918,7 +920,8 @@ function MMI.fit(transformer::ContinuousEncoder, verbosity::Int, X)
     # fit the one-hot encoder:
     hot_encoder =
         OneHotEncoder(ordered_factor=transformer.one_hot_ordered_factors,
-                      drop_last=transformer.drop_last)
+                      drop_last=transformer.drop_last,
+                      datatype=transformer.datatype)
     hot_fitresult, _, hot_report = MMI.fit(hot_encoder, verbosity - 1, X)
 
     new_features = setdiff(hot_report.new_features, features_to_be_dropped)
@@ -957,8 +960,15 @@ function MMI.transform(transformer::ContinuousEncoder, fitresult, X)
     X1 = transform(hot_encoder, hot_fitresult, X0)
 
     # convert remaining to continuous:
-    return coerce(X1, Count=>Continuous, OrderedFactor=>Continuous)
-
+    X2 = coerce(X1, Count=>Continuous, OrderedFactor=>Continuous)
+    if transformer.datatype == Float64
+        return X2
+    else
+        X3 = map(Tables.columntable(X2)) do c
+            transformer.datatype.(c)
+        end
+        return MMI.table(X3, prototype=X)
+    end
 end