参考 :http://charleshm.github.io/2016/03/Model-Performance/
https://blog.csdn.net/zdy0_2004/article/details/44948511
准确率(accuracy):平常说的正确率= (TP+TN)/(TP+FN+FP+TN)
精确率(precision)(查准率):预测为正的样本中有多少是真正的正样本= TP/(TP+FP)
召回率(recall)(查全率):样本中的正例有多少被预测正确了=TP/(TP+FN)