我有一个scikit学习管道来缩放数字特征和编码分类特征。在我试图实现imblearn中的RandomUnderSampler之前,它运行得很好。我的目标是实现欠采样步骤,因为我的数据集非常不平衡1:1000。在
我确保使用imblearn的Pipeline方法而不是sklearn。下面是我尝试过的代码。在
代码数据工作(使用sklearn管道)而不使用欠采样方法。在
from sklearn.pipeline import Pipeline, FeatureUnion
from sklearn.preprocessing import OneHotEncoder, StandardScaler
from imblearn.pipeline import make_pipeline as make_pipeline_imb
from imblearn.pipeline import Pipeline as Pipeline_imb
from sklearn.base import BaseEstimator, TransformerMixin
class TypeSelector(BaseEstimator, TransformerMixin):
def __init__(self, dtype):
self.dtype = dtype
def fit(self, X, y=None):
return self
def transform(self, X):
assert isinstance(X, pd.DataFrame)
return X.select_dtypes(include=[self.dtype])
transformer = Pipeline([
# Union numeric, categoricals and boolean
('features', FeatureUnion(n_jobs=1, transformer_list=[
# Select bolean features
('boolean', Pipeline([
('selector', TypeSelector('bool')),
])),
# Select and scale numericals
('numericals', Pipeline([
('selector', TypeSelector(np.number)),
('scaler', StandardScaler()),
])),
# Select and encode categoricals
('categoricals', Pipeline([
('selector', TypeSelector('category')),
('encoder', OneHotEncoder(handle_unknown='ignore')),
]))
])),
])
pipe = Pipeline([('prep', transformer),
('clf', RandomForestClassifier(n_estimators=500, class_weight='balanced'))
])
使用欠采样方法(使用imblearn管道)无法工作的代码。在
^{pr2}$以下是我得到的错误:
/usr/local/lib/python3.6/dist-packages/sklearn/pipeline.py in __init__(self, steps, memory, verbose)
133 def __init__(self, steps, memory=None, verbose=False):
134 self.steps = steps
--> 135 self._validate_steps()
136 self.memory = memory
137 self.verbose = verbose
/usr/local/lib/python3.6/dist-packages/imblearn/pipeline.py in _validate_steps(self)
144 if isinstance(t, pipeline.Pipeline):
145 raise TypeError(
--> 146 "All intermediate steps of the chain should not be"
147 " Pipelines")
148
TypeError: All intermediate steps of the chain should not be Pipelines
如果您研究文件
imblearn/pipeline.py
here中的imblen代码,在函数_validate_steps
下,他们将检查transformers
中的每一项是否有一个转换器是scikit管道的实例(isinstance(t, pipeline.Pipeline)
)。在从您的代码中,
transformers
是RandomUnderSampler
transformer
类
Pipeline_imb
继承scikit的管道,而在代码中使用Pipeline_imb
是多余的。在已经说过,我会调整你的代码如下
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