经过一些研究,这就是我得出的结论:
from sklearn.cross_validation import ShuffleSplit
from collections import defaultdict
names = db_train.iloc[:,1:].columns.tolist()
# -- Gridsearched parameters
model_rf = RandomForestClassifier(n_estimators=500,
class_weight="auto",
criterion='gini',
bootstrap=True,
max_features=10,
min_samples_split=1,
min_samples_leaf=6,
max_depth=3,
n_jobs=-1)
scores = defaultdict(list)
# -- Fit the model (could be cross-validated)
rf = model_rf.fit(X_train, Y_train)
acc = roc_auc_score(Y_test, rf.predict(X_test))
for i in range(X_train.shape[1]):
X_t = X_test.copy()
np.random.shuffle(X_t[:, i])
shuff_acc = roc_auc_score(Y_test, rf.predict(X_t))
scores[names[i]].append((acc-shuff_acc)/acc)
print("Features sorted by their score:")
print(sorted([(round(np.mean(score), 4), feat) for
feat, score in scores.items()], reverse=True))
Features sorted by their score:
[(0.0028999999999999998, 'Var1'), (0.0027000000000000001, 'Var2'), (0.0023999999999999998, 'Var3'), (0.0022000000000000001, 'Var4'), (0.0022000000000000001, 'Var5'), (0.0022000000000000001, 'Var6'), (0.002, 'Var7'), (0.002, 'Var8'), ...]
scoring
只是一个用于测试样本的性能评估工具,并不会在每个分裂节点内部进入DecisionTreeClassifier
算法。您只能指定criterion
(每个分裂节点的内部损失函数类型)作为树算法的gini
或information entropy
。
scoring
可用于交叉验证环境中,其目标是调整一些超参数(例如max_depth
)。在您的情况下,您可以使用GridSearchCV
来使用得分函数roc_auc
来调整一些超参数。
from sklearn.metrics import roc_auc_score
- lstoddeli5
包中使用。 - Love-R