机器学习：scikit-learn 做笑脸识别 (SVM, KNN, Logisitc regression)

scikit-learn 是 Python 非常强大的一个做机器学习的包，今天介绍scikit-learn 里几个常用的分类器

SVM, KNN 和 logistic regression，用来做笑脸识别。

这里用到的是GENKI4K 这个数据库，每张图像先做一个人脸检测与剪切，然后提取HOG特征。这个数据库有 4000 张图，分成4组，做一个 cross validation，取平均值作为最终的识别率:

import string, os, sys
import numpy as np
import matplotlib.pyplot as plt
import scipy.io
import random
from sklearn import neighbors, linear_model, svm
dir = '/GENKI4K/Feature_Data'
print '----------- no sub dir'  
# prepare the data
files = os.listdir(dir)
for f in files:
    print dir + os.sep + f
file_path=dir+os.sep+files[14]
#print file_path
dic_mat = scipy.io.loadmat(file_path)
data_mat=dic_mat['Hog_Feat']
print 'feature: ',  data_mat.shape
#print data_mat.dtype
file_path2=dir+os.sep+files[15]
#print file_path2
dic_label=scipy.io.loadmat(file_path2)
label_mat=dic_label['Label']
file_path3=dir+os.sep+files[16]
print 'fiel 3 path: ', file_path3
dic_T=scipy.io.loadmat(file_path3)
T=dic_T['T']
T=T-1
print T.shape
label=label_mat.ravel()
# Acc=np.zeros((1,4))
Acc=[0,0,0,0]
for i in range (0, 4):
    print "the fold %d" % (i+1)
    train_ind=[]
    for j in range (0, 4):
        if j==i:
            test_ind=T[j]
        else:
            train_ind.extend(T[j])
#    print len(test_ind), len(train_ind)
#    print max(test_ind), max(train_ind)
    train_x=data_mat[train_ind, :]
    test_x=data_mat[test_ind, :]
    train_y=label[train_ind]
    test_y=label[test_ind]
#   SVM
    clf=svm.LinearSVC()
#   KNN
#    clf = neighbors.KNeighborsClassifier(n_neighbors=15)
#    Logistic regression
#    clf = linear_model.LogisticRegression()
    clf.fit(train_x, train_y)
    predict_y=clf.predict(test_x)
    Acc[i]=np.mean(predict_y == test_y)
    print "Accuracy: %.2f" % (Acc[i])
print "The mean average classification accuracy: %.2f" % (np.mean(Acc))
# SVM 的实验结果
(4, 1000)
the fold 1
Accuracy: 0.89
the fold 2
Accuracy: 0.88
the fold 3
Accuracy: 0.89
the fold 4
Accuracy: 0.90
The mean average classification accuracy: 0.89
# KNN 的实验结果
(4, 1000)
the fold 1
Accuracy: 0.83
the fold 2
Accuracy: 0.84
the fold 3
Accuracy: 0.84
the fold 4
Accuracy: 0.85
The mean average classification accuracy: 0.84
# logistic regression 的实验结果
(4, 1000)
the fold 1
Accuracy: 0.91
the fold 2
Accuracy: 0.91
the fold 3
Accuracy: 0.90
the fold 4
Accuracy: 0.92
The mean average classification accuracy: 0.91