cross_val_score 正在返回 scikit learn 中的 nan 分数列表

Question

我正在尝试使用 cross validation 处理不平衡的 multi label dataset，但 scikit learn cross_val_score 在运行分类器时返回 nan list of values。 代码如下：

import pandas as pd
import numpy as np
data = pd.DataFrame.from_dict(dict, orient = 'index') # save the given data below in dict variable to run this line

from sklearn.model_selection import train_test_split
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.preprocessing import MultiLabelBinarizer
from sklearn.multiclass import OneVsRestClassifier

multilabel = MultiLabelBinarizer()
y = multilabel.fit_transform(data['Tags']) 
from nltk.corpus import stopwords 
stop_words = set(stopwords.words('english')) 
tfidf = TfidfVectorizer(stop_words = stop_words,max_features= 40000, ngram_range = (1,3))
X = tfidf.fit_transform(data['cleaned_title'])

from skmultilearn.model_selection import IterativeStratification
k_fold = IterativeStratification(n_splits=10, order=1)


from sklearn.linear_model import LogisticRegression
from sklearn.metrics import jaccard_score
class_weight = {0:1,1:10}
lr = LogisticRegression(class_weight = class_weight, n_jobs = -1)
scores = cross_val_score(lr, X, y, cv=k_fold, scoring = 'f1_micro')
scores

这是使用data.head(10).to_dict()的数据（前10行）

{0: {'Tags': ['python', 'list', 'loops', 'for-loop', 'indexing'],
  'cleaned_title': 'for loop we use any local variable   what if we use any number present in a list  ',
  'cleaned_text_of_ques': 'in the for   loop we use any local variable   what if we use any number in a list   what will be the output   a   [ 1 2 3 4 5 6 ] b   [ ] for a[ 1 ] in a   b append a[ 1 ]   print b  '},
 1: {'Tags': ['python', 'loops', 'tkinter', 'algorithm-animation'],
  'cleaned_title': 'contain a mainloop [ duplicate ]',
  'cleaned_text_of_ques': 'my code be a bubble sort that i be try to visualise   but i be struggle to find a way to make a block of code only be use once   i also think that if i could only mainloop a section that would'},
 2: {'Tags': ['android',
   'android-lifecycle',
   'activity-lifecycle',
   'onsaveinstancestate'],
  'cleaned_title': 'when onrestoreinstancestate be not call  ',
  'cleaned_text_of_ques': 'docs describe when onrestoreinstancestate be call   this method be call after onstart     when the activity be be re   initialize from a previously save state   give here in savedinstancestate  '},
 3: {'Tags': ['python', 'r', 'bash', 'conda', 'spyder'],
  'cleaned_title': 'point conda r to already   instal version of r',
  'cleaned_text_of_ques': 'my problem have to do with the fact that rstudio and conda be point to different version of r  my r and rstudio be instal independent of anaconda   and everything be work great   in my    '},
 4: {'Tags': ['android',
   'firebase',
   'firebase-realtime-database',
   'android-recyclerview'],
  'cleaned_title': 'how to use a recycleview with several different layout   accord to the datum collect in firebase   [ close ]',
  'cleaned_text_of_ques': 'i have a problem   there be day that i do research and test code   but nothing work   my application will have a window where i will post datum take in firebase   use a recycleview   with the'},
 5: {'Tags': ['html', 'css', 'layout'],
  'cleaned_title': 'how to create side by side layout of an image and label  ',
  'cleaned_text_of_ques': 'i have be try for a while now and can not seem to achive the bellow design    exploreitem   background   color     353258       rgba 31   31   31   1       border   1px solid   4152f1   color  '},
 6: {'Tags': ['php', 'jquery', 'file'],
  'cleaned_title': 'php jquery ajax   _ files[ file   ] undefined index error',
  'cleaned_text_of_ques': 'i have a form that upload image file and it be not work   i have try submit and click event   the error appear when i have remove the if statement   thank in advance for your help  '},
 7: {'Tags': ['python', 'pandas', 'dataframe'],
  'cleaned_title': 'how to update value in pandas dataframe in a for loop  ',
  'cleaned_text_of_ques': 'i be try to make a data frame that can store variable coeff value after each iteration   i be able to plot the graph after each iteration   but when i try to insert the value in the data frame'},
 8: {'Tags': ['xpath', 'web-scraping', 'scrapy'],
  'cleaned_title': 'scrapy   how can i handle a random number of element  ',
  'cleaned_text_of_ques': 'i have a scrapy crawler that i can comfortably acquire the first desire paragraph   but sometimes there be a second or third paragraph   response xpath f string   h2[contains text           card   ] '},
 9: {'Tags': ['bootstrap-4', 'tabs', 'collapse'],
  'cleaned_title': 'collapse three column with bootstrap',
  'cleaned_text_of_ques': 'i be try to make three tab with cross   reference with one tab visible at the time   i be use the bootstrap v4 collapse scheme with functionality support by jquery   here be the example   https  '}}

这就是我在scores 变量中获得cross_val_score 的方式 array([nan, nan, nan, nan, nan, nan, nan, nan, nan, nan])。它的每个值都应该在0-1 范围内。但是，every algorithm model 正在发生这种情况。

Answer 1

您有一个多标签数据集，这意味着您的 y 变量在转换后将有超过 1 列，逻辑回归不适用于它：

lr.fit(X,y)

ValueError: y should be a 1d array, got an array of shape (10, 32) instead.

这就是你得到 nan 的原因。您需要选择一个分类器，有关选项，请参阅the sklearn helpage 。另外，我不确定IterativeStratification 是否适用于多标签，所以如果你使用 KFold 它可以工作：

from sklearn.tree import DecisionTreeClassifier
from sklearn.model_selection import KFold
kf = KFold(n_splits=5)

clf = DecisionTreeClassifier()
scores = cross_val_score(clf, X, y, cv=kf, scoring = 'f1_micro')

Answer 2

我认为您需要更改分数线内的模型：

scores = cross_val_score(lr, X, y, cv=k_fold, scoring = 'f1_micro')
scores