from copy import deepcopy

def dummy_encode_categorical_columns(df, categorical_columns):
    result_df = deepcopy(df)
   #print result_df
    for column in categorical_columns:
        result_df = pd.concat([result_df, pd.get_dummies(result_df[column],
            prefix=column, prefix_sep=': ')], axis=1)
        del result_df[column]
    return result_df

categorical_columns = set(df_train.columns[df_train.dtypes == 'object'])
#print 'before',df_train
df_no_cat = dummy_encode_categorical_columns(df_train, categorical_columns)
X_train=df_no_cat.values.astype(np.float32)