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我正在使用SciKit-Learn 0.18.1和Python 2.7进行一些基本的机器学习。我试图通过交叉验证来评估我的模型有多好。当我这样做:SciKit-Learn:交叉验证的结果非常不同
from sklearn.cross_validation import cross_val_score, KFold
cv = KFold(n=5, random_state = 100)
clf = RandomForestRegressor(n_estimators=400, max_features = 0.5, verbose = 2, max_depth=30, min_samples_leaf=3)
score = cross_val_score(estimator = clf, X = X, y = y, cv = cv, n_jobs = -1,
scoring = "neg_mean_squared_error")
avg_score = np.mean([np.sqrt(-x) for x in score])
std_dev = y.std()
print "avg_score: {}, std_dev: {}, avg_score/std_dev: {}".format(avg_score, std_dev, avg_score/std_dev)
我得到一个低avg_score
(〜9K)。
令人不安的是,尽管指定了5次折叠,但我的score
数组中只有3个项目。相反,当我这样做:
from sklearn.model_selection import KFold, cross_val_score
并运行相同的代码(除n
成为n_splits
),我得到一个更糟糕的方式RMSE(〜24K)。
任何想法这里发生了什么?
谢谢!
请注意,我第一次做'从sklearn.cross_validation进口cross_val_score,KFold'所以它应该是'N' – bclayman
在这种情况下,不是n实例的数量和n_folds数的褶皱? –
此外,http://scikit-learn.org/stable/modules/generated/sklearn.cross_validation.KFold.html#sklearn.model_selection.KFold让我觉得sklearn.cross_validation.KFold已弃用 –