训练集分割成训练集与测试集，代码封装
import numpy as np
def train_test_split(X,y,test_ratio=0.2,seed=None):
"""将数据X与y按照test_ratio分割成X_train,X_test,y_train,y_test"""
assert X.shape[0] == y.shape[0], "the size of X must equal to the sise of y"
assert 0.0 <=test_ratio <= 1.0,"test_ratio must be valid"
if seed:
np.random.seed(seed)
shuffled_index=np.random.permutation(len(X))
test_size=int(len(X)*test_ratio)
test_index=shuffled_index[:test_size]
train_index=shuffled_index[test_size:]
X_train=X[train_index]
y_train=y[train_index]
X_test=X[test_index]
y_test=y[test_index]
return X_train,X_test,y_train,y_testimport numpy as np
def tr 
