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我正在使用SciKit-Learn 0.18.1和Python 2.7進行一些基本的機器學習。我試圖通過交叉驗證來評估我的模型有多好。當我這樣做:SciKit-Learn:交叉驗證的結果非常不同
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)
我得到一個低avg_score
(〜9K)。
令人不安的是,儘管指定了5次摺疊,但我的score
數組中只有3個項目。相反,當我這樣做:
from sklearn.model_selection import KFold, cross_val_score
並運行相同的代碼(除n
成爲n_splits
),我得到一個更糟糕的方式RMSE(〜24K)。
任何想法這裏發生了什麼?
謝謝!
請注意,我第一次做'從sklearn.cross_validation進口cross_val_score,KFold'所以它應該是'N' – bclayman
在這種情況下,不是n實例的數量和n_folds數的褶皺? –
此外,http://scikit-learn.org/stable/modules/generated/sklearn.cross_validation.KFold.html#sklearn.model_selection.KFold讓我覺得sklearn.cross_validation.KFold已棄用 –