问题描述
使用Sklearn进行分层kfold拆分,当我尝试使用多类进行拆分时,收到错误消息(请参见下文).当我尝试使用二进制文件进行拆分时,它没有问题.
Working with Sklearn stratified kfold split, and when I attempt to split using multi-class, I received on error (see below). When I tried and split using binary, it works no problem.
num_classes = len(np.unique(y_train))
y_train_categorical = keras.utils.to_categorical(y_train, num_classes)
kf=StratifiedKFold(n_splits=5, shuffle=True, random_state=999)
# splitting data into different folds
for i, (train_index, val_index) in enumerate(kf.split(x_train, y_train_categorical)):
x_train_kf, x_val_kf = x_train[train_index], x_train[val_index]
y_train_kf, y_val_kf = y_train[train_index], y_train[val_index]
ValueError: Supported target types are: ('binary', 'multiclass'). Got 'multilabel-indicator' instead.
推荐答案
keras.utils.to_categorical
生成一个单编码的类矢量,即错误消息中提到的multilabel-indicator
. StratifiedKFold
不适用于此类输入.从split
方法文档中:
keras.utils.to_categorical
produces a one-hot encoded class vector, i.e. the multilabel-indicator
mentioned in the error message. StratifiedKFold
is not designed to work with such input; from the split
method docs:
[...]
y :类似数组的形状(n_samples个)
y : array-like, shape (n_samples,)
监督学习问题的目标变量.根据y标签进行分层.
The target variable for supervised learning problems. Stratification is done based on the y labels.
即您的y
必须是类标签的一维数组.
i.e. your y
must be a 1-D array of your class labels.
本质上,您要做的只是简单地反转操作顺序:先拆分(使用初始y_train
),然后再转换to_categorical
.
Essentially, what you have to do is simply to invert the order of the operations: split first (using your intial y_train
), and convert to_categorical
afterwards.
这篇关于Sklearn StratifiedKFold:ValueError:支持的目标类型为:("binary","multiclass").改为使用"multilabel-indicator"的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!