我正在尝试使用GridSearchCV和Pipeline构建一个多输出模型 . Pipeline给我带来麻烦,因为标准分类器示例没有包装分类器的OneVsRestClassifier() . 我正在使用scikit-learn 0.18和python 3.5
## Pipeline: Train and Predict
## SGD: support vector machine (SVM) with gradient descent
from sklearn.multiclass import OneVsRestClassifier
from sklearn.pipeline import Pipeline
from sklearn.linear_model import SGDClassifier
clf = Pipeline([
('vect', CountVectorizer(ngram_range=(1,3), max_df=0.50 ) ),
('tfidf', TfidfTransformer() ),
('clf', SGDClassifier(loss='modified_huber', penalty='elasticnet',
alpha=1e-4, n_iter=5, random_state=42,
shuffle=True, n_jobs=-1) ),
])
ovr_clf = OneVsRestClassifier(clf )
from sklearn.model_selection import GridSearchCV
parameters = {'vect__ngram_range': [(1,1), (1,3)],
'tfidf__norm': ('l1', 'l2', None),
'estimator__loss': ('modified_huber', 'hinge',),
}
gs_clf = GridSearchCV(estimator=pipeline, param_grid=parameters,
scoring='f1_weighted', n_jobs=-1, verbose=1)
gs_clf = gs_clf.fit(X_train, y_train)
但这会产生错误:....
ValueError:估算器管道的无效参数估计器(steps = [('vect',CountVectorizer(analyzer ='word',binary = False,decode_error ='strict',dtype =,encoding ='utf-8',input =' content',lowercase = True,max_df = 0.5,max_features = None,min_df = 1,ngram_range =(1,3),preprocessor = None,stop_words = None,strip ... er_t = 0.5,random_state = 42,shuffle = True ,verbose = 0,warm_start = False),n_jobs = -1))]) . 使用estimator.get_params() . keys()检查可用参数列表 .
那么使用param_grid和Pipeline通过OneVsRestClassifier将参数传递给clf的正确方法是什么?我是否需要将矢量化器和tdidf与管道中的分类器分开?
1 回答
将OneVsRestClassifier()作为管道本身的一步,将SGDClassifier作为OneVsRestClassifier的估算器 . 你可以这样 .
其余代码可以保持不变 . OneVsRestClassifier充当其他估算器的包装器 .