[PYTHON] 100 language processing knock-77 (using scikit-learn): measurement of correct answer rate

This is the record of the 77th "Measurement of accuracy rate" of Language processing 100 knocks 2015. The content of the knock question is the measurement of the correct answer rate for the training data, but this time we dare to use the test data as in the previous time. Until now, I didn't post it to the block because it was basically the same as "Amateur language processing 100 knocks". , "Chapter 8: Machine Learning" has been taken seriously and changed to some extent. I will post. I mainly use scikit-learn.

• The next 78th "5-fold cross-validation" will not be performed. This is because it is useless because the 5-fold cross-validation is already performed using the GridSearchCV function during training (to be exact, I did not do it without finding the precision rate etc. with the 5-fold cross-validation, but it is troublesome so I will omit it To do).

Reference link

environment

In the above environment, I am using the following additional Python packages. Just install with regular pip.

Task

Chapter 8: Machine Learning

In this chapter, [sentence polarity dataset] of Movie Review Data published by Bo Pang and Lillian Lee. v1.0](http://www.cs.cornell.edu/people/pabo/movie-review-data/rt-polaritydata.README.1.0.txt) is used to make the sentence positive or negative. Work on the task (polarity analysis) to classify as (negative).

77. Measurement of correct answer rate

Create a program that receives output of> 76 and calculates the correct answer rate of the prediction, the correct answer rate for the correct example, the recall rate, and the F1 score.

This time, I ignored the part "Receive 76 outputs" and implemented it for the test data. Like last time, I thought that test data would be more useful than training data.

Answer

Answer program [077. Measurement of correct answer rate.ipynb](https://github.com/YoheiFukuhara/nlp100/blob/master/08.%E6%A9%9F%E6%A2%B0%E5%AD%A6% E7% BF% 92 / 077.% E6% AD% A3% E8% A7% A3% E7% 8E% 87% E3% 81% AE% E8% A8% 88% E6% B8% AC.ipynb)

Basically [previous "076. Labeling.ipynb"](https://github.com/YoheiFukuhara/nlp100/blob/master/08.%E6%A9%9F%E6%A2%B0%E5%AD % A6% E7% BF% 92 / 076.% E3% 83% A9% E3% 83% 99% E3% 83% AB% E4% BB% 98% E3% 81% 91.ipynb) Correct answer rate and related indicators It's just about adding output logic.

import csv

import pandas as pd
import matplotlib.pyplot as plt
import numpy as np
from sklearn.feature_extraction.text import CountVectorizer, TfidfVectorizer
from sklearn.linear_model import LogisticRegression
from sklearn.model_selection import GridSearchCV, train_test_split
from sklearn.metrics import classification_report, confusion_matrix
from sklearn.pipeline import Pipeline
from sklearn.base import BaseEstimator, TransformerMixin

#Classes for using word vectorization in GridSearchCV
class myVectorizer(BaseEstimator, TransformerMixin):
    def __init__(self, method='tfidf', min_df=0.0005, max_df=0.10):
        self.method = method
        self.min_df = min_df
        self.max_df = max_df

    def fit(self, x, y=None):
        if self.method == 'tfidf':
            self.vectorizer = TfidfVectorizer(min_df=self.min_df, max_df=self.max_df)
        else:
            self.vectorizer = CountVectorizer(min_df=self.min_df, max_df=self.max_df)
        self.vectorizer.fit(x)
        return self

    def transform(self, x, y=None):
        return self.vectorizer.transform(x)
		
#Parameters for GridSearchCV
PARAMETERS = [
    {
        'vectorizer__method':['tfidf', 'count'], 
        'vectorizer__min_df': [0.0003, 0.0004], 
        'vectorizer__max_df': [0.07, 0.10], 
        'classifier__C': [1, 3],    #I also tried 10 but the SCORE is low just because it is slow
        'classifier__solver': ['newton-cg', 'liblinear']},
    ]

#Read file
def read_csv_column(col):
    with open('./sentiment_stem.txt') as file:
        reader = csv.reader(file, delimiter='\t')
        header = next(reader)
        return [row[col] for row in reader]    
		
x_all = read_csv_column(1)
y_all = read_csv_column(0)
x_train, x_test, y_train, y_test = train_test_split(x_all, y_all)

def train(x_train, y_train, file):
    pipline = Pipeline([('vectorizer', myVectorizer()), ('classifier', LogisticRegression())])
    
    #clf stands for classification
    clf = GridSearchCV(
            pipline, # 
            PARAMETERS,           #Parameter set you want to optimize
            cv = 5)               #Number of cross-validations
    
    clf.fit(x_train, y_train)
    pd.DataFrame.from_dict(clf.cv_results_).to_csv(file)

    print('Grid Search Best parameters:', clf.best_params_)
    print('Grid Search Best validation score:', clf.best_score_)
    print('Grid Search Best training score:', clf.best_estimator_.score(x_train, y_train))    
    
    #Feature weight output
    output_coef(clf.best_estimator_)
    
    return clf.best_estimator_

#Feature weight output
def output_coef(estimator):
    vec = estimator.named_steps['vectorizer']
    clf = estimator.named_steps['classifier']

    coef_df = pd.DataFrame([clf.coef_[0]]).T.rename(columns={0: 'Coefficients'})
    coef_df.index = vec.vectorizer.get_feature_names()
    coef_sort = coef_df.sort_values('Coefficients')
    coef_sort[:10].plot.barh()
    coef_sort.tail(10).plot.barh()

def validate(estimator, x_test, y_test):
    
    for i, (x, y) in enumerate(zip(x_test, y_test)):
        y_pred = estimator.predict_proba([x])
        if y == np.argmax(y_pred).astype( str ):
            if y == '1':
                result = 'TP:The correct answer is Positive and the prediction is Positive'
            else:
                result = 'TN:The correct answer is Negative and the prediction is Negative'
        else:
            if y == '1':
                result = 'FN:The correct answer is Positive and the prediction is Negative'
            else:
                result = 'FP:The correct answer is Negative and the prediction is Positive'
        print(result, y_pred, x)
        if i == 29:
            break

    #TSV list output
    y_pred = estimator.predict(x_test)
    y_prob = estimator.predict_proba(x_test)

    results = pd.DataFrame([y_test, y_pred, y_prob.T[1], x_test]).T.rename(columns={ 0: 'Correct answer', 1 : 'Forecast', 2: 'Forecast確率(positive)', 3 :'Word string'})
    results.to_csv('./predict.txt' , sep='\t')

    print('\n', classification_report(y_test, y_pred))
    print('\n', confusion_matrix(y_test, y_pred))

estimator = train(x_train, y_train, 'gs_result.csv')
validate(estimator, x_test, y_test)

Answer commentary

I'm just using scikit-learn's classification_report, and I haven't written much about it. The result y_pred of the predict function used in the previous "labeling" is used.

y_pred = estimator.predict(x_test)

All you have to do now is pass it to the classification_report function with the original correct label y_test.

print('\n', classification_report(y_test, y_pred))

The precision rate, recall rate, F1 score, correct answer rate, etc. are output.

              precision    recall  f1-score   support

           0       0.75      0.73      0.74      1351
           1       0.73      0.75      0.74      1315

    accuracy                           0.74      2666
   macro avg       0.74      0.74      0.74      2666
weighted avg       0.74      0.74      0.74      2666

Since the parameters to be passed are the same, the confusion_matrix function also outputs the confusion matrix.

print('\n', confusion_matrix(y_test, y_pred))

A mixed matrix appears in a simple form. For details on the mixed matrix, see [Separate article "[For beginners] Explanation of evaluation indicators for classification problems in machine learning (correct answer rate, precision rate, recall rate, etc.)" (https://qiita.com/FukuharaYohei/items/be89a99c53586fa4e2e4) ).

 [[992 359]
 [329 986]]