面对ValueError:目标是多类的,但average ='binary'


问题内容

我是python以及机器学习的新手。根据我的要求,我正在尝试对数据集使用朴素贝叶斯算法。

我能够找出准确度,但尝试找出准确度并回想一下。但是,它引发以下错误:

   "choose another average setting." % y_type)
ValueError: Target is multiclass but average='binary'. Please choose another average setting.

谁能建议我如何进行。我曾尝试在平均值和召回率分数中使用average
=’micro’。它的工作原理没有任何错误,但在准确性,准确性和召回率上却给出了相同的分数。

我的数据集:

train_data.csv:

review,label
Colors & clarity is superb,positive
Sadly the picture is not nearly as clear or bright as my 40 inch Samsung,negative

test_data.csv:

review,label
The picture is clear and beautiful,positive
Picture is not clear,negative

我的代码:

from sklearn.preprocessing import MultiLabelBinarizer
from sklearn.model_selection import train_test_split
from sklearn.naive_bayes import BernoulliNB
from sklearn.metrics import confusion_matrix
from sklearn.feature_extraction.text import CountVectorizer
from sklearn.naive_bayes import MultinomialNB
from sklearn.metrics import precision_score
from sklearn.metrics import recall_score


def load_data(filename):
    reviews = list()
    labels = list()
    with open(filename) as file:
        file.readline()
        for line in file:
            line = line.strip().split(',')
            labels.append(line[1])
            reviews.append(line[0])

    return reviews, labels

X_train, y_train = load_data('/Users/abc/Sep_10/train_data.csv')
X_test, y_test = load_data('/Users/abc/Sep_10/test_data.csv')

vec = CountVectorizer()

X_train_transformed =  vec.fit_transform(X_train)

X_test_transformed = vec.transform(X_test)

clf= MultinomialNB()
clf.fit(X_train_transformed, y_train)

score = clf.score(X_test_transformed, y_test)
print("score of Naive Bayes algo is :" , score)

y_pred = clf.predict(X_test_transformed)
print(confusion_matrix(y_test,y_pred))

print("Precision Score : ",precision_score(y_test,y_pred,pos_label='positive'))
print("Recall Score :" , recall_score(y_test, y_pred, pos_label='positive') )

问题答案:

您需要添加'average'参数。根据文档

平均值: 字符串,[无,“二进制”(默认),“微”,“宏”,“样本”,“加权”]

对于多类/多标签目标,此参数是必需的。如果为None,则返回每个班级的分数。否则,这将确定对数据执行的平均类型:

做这个:

print("Precision Score : ",precision_score(y_test, y_pred, 
                                           pos_label='positive'
                                           average='micro'))
print("Recall Score : ",recall_score(y_test, y_pred, 
                                           pos_label='positive'
                                           average='micro'))

替换'micro'为以上任一选项'binary'。同样,在多类设置中,不需要提供,'pos_label'因为无论如何它将被忽略。

更新评论:

是的,它们可以相等。它在用户指南中给出:

请注意,对于包含所有标签的多类设置中的“微”平均,将产生相等的精度,召回率和F,而“加权”平均可能产生不在精度和召回率之间的F分数。