将分类器投入生产


问题内容

我已经使用joblib保存了分类器管道:

vec = TfidfVectorizer(sublinear_tf=True, max_df=0.5, ngram_range=(1, 3))
pac_clf = PassiveAggressiveClassifier(C=1)
vec_clf = Pipeline([('vectorizer', vec), ('pac', pac_clf)])
vec_clf.fit(X_train,y_train)
joblib.dump(vec_clf, 'class.pkl', compress=9)

现在,我试图在生产环境中使用它:

def classify(title):

  #load classifier and predict
  classifier = joblib.load('class.pkl')

  #vectorize/transform the new title then predict
  vectorizer = TfidfVectorizer(sublinear_tf=True, max_df=0.5, ngram_range=(1, 3))
  X_test = vectorizer.transform(title)
  predict = classifier.predict(X_test)
  return predict

我得到的错误是:ValueError:词汇不适合或为空!我想我应该从Joblid加载词汇,但是我无法使它正常工作


问题答案:

只需替换:

  #load classifier and predict
  classifier = joblib.load('class.pkl')

  #vectorize/transform the new title then predict
  vectorizer = TfidfVectorizer(sublinear_tf=True, max_df=0.5, ngram_range=(1, 3))
  X_test = vectorizer.transform(title)
  predict = classifier.predict(X_test)
  return predict

通过:

  # load the saved pipeline that includes both the vectorizer
  # and the classifier and predict
  classifier = joblib.load('class.pkl')
  predict = classifier.predict(X_test)
  return predict

class.pkl包括完整的管道,因此无需创建新的矢量化器实例。如错误消息所述,您需要重用最初训练的矢量化程序,因为从令牌(字符串ngram)到列索引的特征映射保存在矢量化程序本身中。此映射称为“词汇表”。