Scikit-learn TransformerMixin ： 'numpy.ndarray'对象没有属性'fit'

Question

我想构建一个sklearn管道（一个更大的管道的一部分），它：

1. 编码分类列 （OneHotEncoder）
2. 减小尺寸 （SVD）
3. 添加数字列（不进行转换）
4. 聚合行（熊猫分组）

我使用了这个管道示例：

以及这个自定义 TranformerMixin 的例子：

我在步骤 4

中收到错误（如果我评论步骤 4 则没有错误）：

属性错误回溯（最近一次调用） 最后） 在 （） 中 ----> 1 X_train_transformed = pipe.fit_transform（X_train） ....属性错误："numpy.ndarray"对象没有属性"fit"

我的代码 ：

from sklearn.pipeline import Pipeline
from sklearn.preprocessing import OneHotEncoder
from sklearn.decomposition import TruncatedSVD
from sklearn.base import BaseEstimator, TransformerMixin
from sklearn.compose import ColumnTransformer
# does nothing, but is here to collect numerical columns
class nothing(BaseEstimator, TransformerMixin):
    def fit(self, X, y=None):       
        return self
    def transform(self, X):          
        return X

class Aggregator(BaseEstimator, TransformerMixin):
    def fit(self, X, y=None):
        return self
    def transform(self, X):
        X = pd.DataFrame(X)
        X = X.rename(columns = {0 :'InvoiceNo', 1 : 'amount', 2:'Quantity', 
                                3:'UnitPrice',4:'CustomerID' })
        X['InvoiceNo'] =  X['InvoiceNo'].astype('int')
        X['Quantity'] = X['Quantity'].astype('float64')
        X['UnitPrice'] = X['UnitPrice'].astype('float64')
        aggregations = dict()
        for col in range(5, X.shape[1]-1) :
            aggregations[col] = 'max'
        aggregations.update({ 'CustomerID' : 'first',
                            'amount' : "sum",'Quantity' : 'mean', 'UnitPrice' : 'mean'})
        # aggregating all basket lines
        result = X.groupby('InvoiceNo').agg(aggregations)
        # add number of lines in the basket
        result['lines_nb'] = X.groupby('InvoiceNo').size()
        return result
        numeric_features = ['InvoiceNo','amount', 'Quantity', 'UnitPrice', 
                           'CustomerID']
        numeric_transformer = Pipeline(steps=[('nothing', nothing())])
        categorical_features = ['StockCode', 'Country']   
        preprocessor =  ColumnTransformer(
        [
        # 'num' transformer does nothing, but is here to  
        # collect numerical columns
        ('num', numeric_transformer ,numeric_features ),
        ('cat', Pipeline([
            ('onehot', OneHotEncoder(handle_unknown='ignore')),
            ('best', TruncatedSVD(n_components=100)),
         ]), categorical_features)        
          ]
          )
# edit with Artem solution
# aggregator = ('agg', Aggregator())
pipe = Pipeline(steps=[
                      ('preprocessor', preprocessor),
                      # edit with Artem solution
                      # ('aggregator', aggregator),
                      ('aggregator', Aggregator())
                     ])
X_train_transformed = pipe.fit_transform(X_train)

Answer 1

管道步骤来自（'name'，Class），但原始任务基本上具有：

aggregator = ('agg', Aggregator())`
pipe = Pipeline(steps=[
                      ('preprocessor', preprocessor),
                      ('aggregator', aggregator),
])

这使它('aggregator', ('agg', Aggregator()))