content: from collections import defaultdict
  import pandas as pd
  import numpy as np
  from sklearn.base import BaseEstimator,TransformerMixin
  from seldon.util import DeprecationHelper
  
  class SklearnTransform(BaseEstimator,TransformerMixin):
      """
      Allow sklearn transformers to be run on Pandas dataframes.
  
      Parameters
      ----------
  
      input_features : list str
         input columns to use
      output_features : list str, optional
         names of output columns
      transformer : scikit learn Transformer
         transformer to run on data
      """
      def __init__(self,input_features=None,output_features=None,output_features_prefix=None,transformer=None):
          self.input_features=input_features
          self.output_features=output_features
          self.transformer=transformer
          self.output_features_prefix=output_features_prefix
  
  
      def fit(self,df):
          """
          Parameters
          ----------
  
          df : pandas dataframe 
  
          Returns
          -------
          self: object
          """
          self.transformer.fit(df[self.input_features].values)
          return self
          
      def transform(self,df):
          """
          transform the input columns and merge result into input dataframe using column names if provided
  
          Parameters
          ----------
  
          df : pandas dataframe 
  
          Returns
          -------
          
          Transformed pandas dataframe
          """
          Y = self.transformer.transform(df[self.input_features].values)
          df_Y = pd.DataFrame(Y)
          if not self.output_features_prefix is None:
              cols = [self.output_features_prefix+"_"+str(c) for c in df_Y.columns]
              df_Y.columns = cols
          elif not self.output_features is None and len(df_Y.columns) == len(self.output_features):
              df_Y.columns = self.output_features
          df_2 = pd.concat([df,df_Y],axis=1)
          return df_2
  
  sklearn_transform = DeprecationHelper(SklearnTransform)