python根据行值添加一列
我有一个数据帧,如下所示。我想根据列“需要”添加一列(例如在第0行中,需要为1,因此选择part1值-0.17。我已经粘贴了我想要的数据框。谢谢python根据行值添加一列,python,pandas,dataframe,Python,Pandas,Dataframe,我有一个数据帧,如下所示。我想根据列“需要”添加一列(例如在第0行中,需要为1,因此选择part1值-0.17。我已经粘贴了我想要的数据框。谢谢 df = pd.DataFrame({ 'date': [20130101,20130101, 20130103, 20130104, 20130105, 20130107], 'need':[1,3,2,4,3,1], 'part1':[-0.17,-1.03,1.59,-0.05,-0.1,0.9
df = pd.DataFrame({
'date': [20130101,20130101, 20130103, 20130104, 20130105, 20130107],
'need':[1,3,2,4,3,1],
'part1':[-0.17,-1.03,1.59,-0.05,-0.1,0.9],
'part2':[0.67,-0.03,1.95,-3.25,-0.3,0.6],
'part3':[0.7,-3,1.5,-0.25,-0.37,0.62],
'part4':[0.24,-0.44,1.335,-0.45,-0.57,0.92]
})
date need output part1 part2 part3 part4
0 20130101 1 -0.17 -0.17 0.67 0.70 0.240
1 20130101 3 -3.00 -1.03 -0.03 -3.00 -0.440
2 20130103 2 1.95 1.59 1.95 1.50 1.335
3 20130104 4 -0.45 -0.05 -3.25 -0.25 -0.450
4 20130105 3 -0.37 -0.10 -0.30 -0.37 -0.570
5 20130107 1 0.90 0.90 0.60 0.62 0.920
使用:
Numpy解决方案是按1
对递增列进行排序所必需的,如示例中所示:
df['new'] = df.filter(like='part').values[np.arange(len(df)), df['need'] - 1]
print (df)
date need part1 part2 part3 part4 new
0 20130101 1 -0.17 0.67 0.70 0.240 -0.17
1 20130101 3 -1.03 -0.03 -3.00 -0.440 -3.00
2 20130103 2 1.59 1.95 1.50 1.335 1.95
3 20130104 4 -0.05 -3.25 -0.25 -0.450 -0.45
4 20130105 3 -0.10 -0.30 -0.37 -0.570 -0.37
5 20130107 1 0.90 0.60 0.62 0.920 0.90
应该没问题
df['new'] = df.iloc[:, 1:].apply(lambda row: row['part'+str(int(row['need']))], axis=1)
date need part1 part2 part3 part4 new
0 20130101 1 -0.17 0.67 0.70 0.240 -0.17
1 20130101 3 -1.03 -0.03 -3.00 -0.440 -3.00
2 20130103 2 1.59 1.95 1.50 1.335 1.95
3 20130104 4 -0.05 -3.25 -0.25 -0.450 -0.45
4 20130105 3 -0.10 -0.30 -0.37 -0.570 -0.37
5 20130107 1 0.90 0.60 0.62 0.920 0.90
这有用吗?
df['new'] = df.iloc[:, 1:].apply(lambda row: row['part'+str(int(row['need']))], axis=1)
date need part1 part2 part3 part4 new
0 20130101 1 -0.17 0.67 0.70 0.240 -0.17
1 20130101 3 -1.03 -0.03 -3.00 -0.440 -3.00
2 20130103 2 1.59 1.95 1.50 1.335 1.95
3 20130104 4 -0.05 -3.25 -0.25 -0.450 -0.45
4 20130105 3 -0.10 -0.30 -0.37 -0.570 -0.37
5 20130107 1 0.90 0.60 0.62 0.920 0.90