scikit-learn 常用分类算法的使用

scikit-learn机器学习的分类算法包括逻辑回归、朴素贝叶斯、KNN、支持向量机、决策树和随机森林等。这些模块的调用形式基本一致，训练用fit方法，预测用predict方法。用joblib.dump方法可以保存训练的模型，用joblib.load方法可以载入模型。

测试程序。测试数据采用小麦种子数据集 （seeds）。

# -*- coding: utf-8 -*-

import numpy as np  
from sklearn.cross_validation import KFold
from sklearn.linear_model import LogisticRegression
from sklearn.naive_bayes import GaussianNB
from sklearn.neighbors import KNeighborsClassifier 
from sklearn import svm
from sklearn.tree import DecisionTreeClassifier
from sklearn.ensemble import RandomForestClassifier

feature_names = [  
    'area',  
    'perimeter',  
    'compactness',  
    'length of kernel',  
    'width of kernel',  
    'asymmetry coefficien',  
    'length of kernel groove',  
]  

COLOUR_FIGURE = False  

def load_csv_data(filename):  
    data = []  
    labels = []  
    datafile = open(filename)  
    for line in datafile:  
        fields = line.strip().split('\t')  
        data.append([float(field) for field in fields[:-1]])  
        labels.append(fields[-1])  
    data = np.array(data)  
    labels = np.array(labels)  
    return data, labels  
    
def accuracy(test_labels, pred_lables):  
    correct = np.sum(test_labels == pred_lables)  
    n = len(test_labels)  
    return float(correct) / n  

#------------------------------------------------------------------------------
#逻辑回归
#------------------------------------------------------------------------------
def testLR(features, labels):
    kf = KFold(len(features), n_folds=3, shuffle=True)  
    clf = LogisticRegression()
    result_set = [(clf.fit(features[train], labels[train]).predict(features[test]), test) for train, test in kf]  
    score = [accuracy(labels[result[1]], result[0]) for result in result_set]  
    print(score)

#------------------------------------------------------------------------------
#朴素贝叶斯
#------------------------------------------------------------------------------
def testNaiveBayes(features, labels):
    kf = KFold(len(features), n_folds=3, shuffle=True)  
    clf = GaussianNB()
    result_set = [(clf.fit(features[train], labels[train]).predict(features[test]), test) for train, test in kf]  
    score = [accuracy(labels[result[1]], result[0]) for result in result_set]  
    print(score)


#------------------------------------------------------------------------------
#K最近邻
#------------------------------------------------------------------------------
def testKNN(features, labels):
    kf = KFold(len(features), n_folds=3, shuffle=True)  
    clf = KNeighborsClassifier(n_neighbors=5) 
    result_set = [(clf.fit(features[train], labels[train]).predict(features[test]), test) for train, test in kf]  
    score = [accuracy(labels[result[1]], result[0]) for result in result_set]  
    print(score)
             
#------------------------------------------------------------------------------
#--- 支持向量机
#------------------------------------------------------------------------------
def testSVM(features, labels):
    kf = KFold(len(features), n_folds=3, shuffle=True)  
    clf = svm.SVC()
    result_set = [(clf.fit(features[train], labels[train]).predict(features[test]), test) for train, test in kf]  
    score = [accuracy(labels[result[1]], result[0]) for result in result_set]  
    print(score)

#------------------------------------------------------------------------------
#--- 决策树
#------------------------------------------------------------------------------
def testDecisionTree(features, labels):
    kf = KFold(len(features), n_folds=3, shuffle=True)  
    clf = DecisionTreeClassifier()
    result_set = [(clf.fit(features[train], labels[train]).predict(features[test]), test) for train, test in kf]  
    score = [accuracy(labels[result[1]], result[0]) for result in result_set]  
    print(score)
    
#------------------------------------------------------------------------------
#--- 随机森林
#------------------------------------------------------------------------------
def testRandomForest(features, labels):
    kf = KFold(len(features), n_folds=3, shuffle=True)  
    clf = RandomForestClassifier()
    result_set = [(clf.fit(features[train], labels[train]).predict(features[test]), test) for train, test in kf]  
    score = [accuracy(labels[result[1]], result[0]) for result in result_set]  
    print(score)

    
if __name__ == '__main__':
    features, labels = load_csv_data('data/seeds_dataset.txt') 
    print(features)
    
    print('LogisticRegression: \r')
    testLR(features, labels)
    
    print('GaussianNB: \r')
    testNaiveBayes(features, labels)
    
    print('KNN: \r')
    testKNN(features, labels)
    
    print('SVM: \r')
    testSVM(features, labels)
    
    print('Decision Tree: \r')
    testDecisionTree(features, labels)
    
    print('Random Forest: \r')
    testRandomForest(features, labels)
    

在Spyder中调试运行，运行结果。

runfile('E:/MyProject/_python/ScikitLearn/demo_clf.py', wdir='E:/MyProject/_python/ScikitLearn')
[[ 15.26    14.84     0.871  ...,   3.312    2.221    5.22  ]
 [ 14.88    14.57     0.8811 ...,   3.333    1.018    4.956 ]
 [ 14.29    14.09     0.905  ...,   3.337    2.699    4.825 ]
 ..., 
 [ 13.2     13.66     0.8883 ...,   3.232    8.315    5.056 ]
 [ 11.84    13.21     0.8521 ...,   2.836    3.598    5.044 ]
 [ 12.3     13.34     0.8684 ...,   2.974    5.637    5.063 ]]
LogisticRegression: 
[0.9142857142857143, 0.9714285714285714, 0.8857142857142857]
GaussianNB: 
[0.9428571428571428, 0.8714285714285714, 0.9]
KNN: 
[0.9285714285714286, 0.8571428571428571, 0.8857142857142857]
SVM: 
[0.9, 0.9285714285714286, 0.8571428571428571]
Decision Tree: 
[0.8714285714285714, 0.9714285714285714, 0.9142857142857143]
Random Forest: 
[0.8857142857142857, 0.9142857142857143, 0.8428571428571429]