sklearn 的train_test_split

train_test_split函数用于将矩阵随机划分为训练子集和测试子集，并返回划分好的训练集测试集样本和训练集测试集标签。

格式：

from sklearn.model_selection import train_test_split

X_train,X_test, y_train, y_test =model_selection.train_test_split(train_data,train_target,test_size=0.3, random_state=0)

　　

自己实现

def train_test_split(x,y,test_ratio=0.2,seed=None):
    assert x.shape[0]==y.shape[0],"the size of x must be equal to the size of y"
    if seed:
        np.random.seed(seed)
    length = len(x)
    index = np.random.permutation(length)
    test_size = int(length*test_ratio)
    test_index = index[:test_size]
    train_index = index[test_size:]

    trainX = x[train_index]
    trainY = y[train_index]
    testX = x[test_index]
    testY = y[test_index]
    return trainX,trainY,testX,testY