pandas 使用 sklearn 的 KFold 分离熊猫数据框
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/45115964/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
提示：将鼠标放在中文语句上可以显示对应的英文。显示中英文
时间：2020-09-14 04:00:53 来源:igfitidea点击:
Separate pandas dataframe using sklearn's KFold
提问by Mervyn Lee
I had obtained the index of training set and testing set with code below.
我已经通过下面的代码获得了训练集和测试集的索引。
df = pandas.read_pickle(filepath + filename)
kf = KFold(n_splits = n_splits, shuffle = shuffle, random_state =
randomState)
result = next(kf.split(df), None)
#train can be accessed with result[0]
#test can be accessed with result[1]
I wonder if there is any faster way to separate them into 2 dataframe respectively with the row indexes I retrieved.
我想知道是否有任何更快的方法将它们分别与我检索到的行索引分成 2 个数据帧。
回答by jezrael
You need DataFrame.ilocfor select rows by positions:
您需要DataFrame.iloc按位置选择行：
Sample:
样品：
np.random.seed(100)
df = pd.DataFrame(np.random.random((10,5)), columns=list('ABCDE'))
df.index = df.index * 10
print (df)
A B C D E
0 0.543405 0.278369 0.424518 0.844776 0.004719
10 0.121569 0.670749 0.825853 0.136707 0.575093
20 0.891322 0.209202 0.185328 0.108377 0.219697
30 0.978624 0.811683 0.171941 0.816225 0.274074
40 0.431704 0.940030 0.817649 0.336112 0.175410
50 0.372832 0.005689 0.252426 0.795663 0.015255
60 0.598843 0.603805 0.105148 0.381943 0.036476
70 0.890412 0.980921 0.059942 0.890546 0.576901
80 0.742480 0.630184 0.581842 0.020439 0.210027
90 0.544685 0.769115 0.250695 0.285896 0.852395
from sklearn.model_selection import KFold
#added some parameters
kf = KFold(n_splits = 5, shuffle = True, random_state = 2)
result = next(kf.split(df), None)
print (result)
(array([0, 2, 3, 5, 6, 7, 8, 9]), array([1, 4]))
train = df.iloc[result[0]]
test = df.iloc[result[1]]
print (train)
A B C D E
0 0.543405 0.278369 0.424518 0.844776 0.004719
20 0.891322 0.209202 0.185328 0.108377 0.219697
30 0.978624 0.811683 0.171941 0.816225 0.274074
50 0.372832 0.005689 0.252426 0.795663 0.015255
60 0.598843 0.603805 0.105148 0.381943 0.036476
70 0.890412 0.980921 0.059942 0.890546 0.576901
80 0.742480 0.630184 0.581842 0.020439 0.210027
90 0.544685 0.769115 0.250695 0.285896 0.852395
print (test)
A B C D E
10 0.121569 0.670749 0.825853 0.136707 0.575093
40 0.431704 0.940030 0.817649 0.336112 0.175410
