我想知道如何使用sklearn.linear_model.LogisticRegression
来训练命名实体识别(NER)的NLP日志线性模型。
用于定义条件概率的典型对数线性模型如下:
使用:
可以sklearn.linear_model.LogisticRegression
训练这样的模型吗?
问题在于功能取决于课程。
答案 0 :(得分:7)
在scikit-learn 0.16及更高版本中,您可以使用multinomial
sklearn.linear_model.LogisticRegression
选项来训练对数线性模型(a.k.a. MaxEnt分类器,多类逻辑回归)。目前,'{lbfgs'和'newton-cg'解算器multinomial
选项为supported only。
Iris数据集示例(4个功能,3个类,150个样本):
#!/usr/bin/python
# -*- coding: utf-8 -*-
from __future__ import print_function
from __future__ import division
import numpy as np
import matplotlib.pyplot as plt
from sklearn import linear_model, datasets
from sklearn.metrics import confusion_matrix
from sklearn.metrics import classification_report
# Import data
iris = datasets.load_iris()
X = iris.data # features
y_true = iris.target # labels
# Look at the size of the feature matrix and the label vector:
print('iris.data.shape: {0}'.format(iris.data.shape))
print('iris.target.shape: {0}\n'.format(iris.target.shape))
# Instantiate a MaxEnt model
logreg = linear_model.LogisticRegression(C=1e5, multi_class='multinomial', solver='lbfgs')
# Train the model
logreg.fit(X, y_true)
print('logreg.coef_: \n{0}\n'.format(logreg.coef_))
print('logreg.intercept_: \n{0}'.format(logreg.intercept_))
# Use the model to make predictions
y_pred = logreg.predict(X)
print('\ny_pred: \n{0}'.format(y_pred))
# Assess the quality of the predictions
print('\nconfusion_matrix(y_true, y_pred):\n{0}\n'.format(confusion_matrix(y_true, y_pred)))
print('classification_report(y_true, y_pred): \n{0}'.format(classification_report(y_true, y_pred)))
multinomial
was introduced in version 0.16的sklearn.linear_model.LogisticRegression
选项:
- 添加
multi_class="multinomial"
选项 :class:linear_model.LogisticRegression
实现Logistic 回归求解器可最大限度地减少交叉熵或多项式损失 而不是默认的One-vs-Rest设置。支持lbfgs
和newton-cg
求解器。按Lars Buitinck
_和Manoj Kumar
_。求解器选项 Simon Wunewton-cg
。