我正在尝试在分组数据上实现交叉验证方案。我希望使用GroupKFold方法,但我一直出现错误。我做错了什么吗? 以下是代码(与我使用的代码略有不同--我的数据不同,因此我有更大的n_splits,但其他所有内容都相同)
from sklearn import metrics
import matplotlib.pyplot as plt
import numpy as np
from sklearn.model_selection import GroupKFold
from sklearn.grid_search import GridSearchCV
from xgboost import XGBRegressor
#generate data
x=np.array([0,1,2,3,4,5,6,7,8,9,10,11,12,13])
y= np.array([1,2,3,4,5,6,7,1,2,3,4,5,6,7])
group=np.array([1,0,1,1,2,2,2,1,1,1,2,0,0,2)]
#grid search
gkf = GroupKFold( n_splits=3).split(x,y,group)
subsample = np.arange(0.3,0.5,0.1)
param_grid = dict( subsample=subsample)
rgr_xgb = XGBRegressor(n_estimators=50)
grid_search = GridSearchCV(rgr_xgb, param_grid, cv=gkf, n_jobs=-1)
result = grid_search.fit(x, y)
错误:
Traceback (most recent call last):
File "<ipython-input-143-11d785056a08>", line 8, in <module>
result = grid_search.fit(x, y)
File "/home/student/anaconda/lib/python3.5/site-packages/sklearn/grid_search.py", line 813, in fit
return self._fit(X, y, ParameterGrid(self.param_grid))
File "/home/student/anaconda/lib/python3.5/site-packages/sklearn/grid_search.py", line 566, in _fit
n_folds = len(cv)
TypeError: object of type 'generator' has no len()
改变这行
gkf = GroupKFold( n_splits=3).split(x,y,group)
gkf = GroupKFold( n_splits=3)
同样没有起作用。然后出现了以下错误信息:
'GroupKFold' object is not iterable
sklearn
版本是哪一个?GridSearchCV
的cv
参数通常需要使用生成器。 - Moses Koledoye