使用 cross_validation.KFold(n, n_folds=folds) 之后,我想访问索引以进行单折叠的训练和测试,而不是遍历所有折叠。
那么我们来看一下示例代码:
from sklearn import cross_validation
X = np.array([[1, 2], [3, 4], [1, 2], [3, 4]])
y = np.array([1, 2, 3, 4])
kf = cross_validation.KFold(4, n_folds=2)
>>> print(kf)
sklearn.cross_validation.KFold(n=4, n_folds=2, shuffle=False,
random_state=None)
>>> for train_index, test_index in kf:
我想像这样访问 kf 中的第一个折叠(而不是 for 循环):
train_index, test_index in kf[0]
这应该只返回第一个折叠,但我收到错误:“TypeError:‘KFold’对象不支持索引”
我想要的输出:
>>> train_index, test_index in kf[0]
>>> print("TRAIN:", train_index, "TEST:", test_index)
TRAIN: [2 3] TEST: [0 1]
Link: http://scikit-learn.org/stable/modules/ generated/sklearn.cross_validation.KFold.html http://scikit-learn.org/stable/modules/generated/sklearn.cross_validation.KFold.html
Question
如何仅检索一次训练和测试的索引,而不经历整个 for 循环?