1. Cross Validation是用来进行交叉验证
先导入一些依赖包
from sklearn.ensemble
import GradientBoostingClassifier
from sklearn.cross_validation
import cross_val_score
from sklearn
import metrics
import numnpy
as np
import pandas
as pd
2. 设置模型和评价指标，开始用不同的参数训练模型
clf = GradientBoostingClassifier()
scores = cross_val_score(clf, X, y, cv=
10, scoring=
"f1")
3. 获取scores的均值
scores.mean()
