我有一个关于数据帧合并的基本问题。在我合并了两个数据帧之后,有没有一种方法可以在结果中只选择几列。
例如:
left = pd.DataFrame({'key1': ['K0', 'K0', 'K1', 'K2'],
'key2': ['K0', 'K1', 'K0', 'K1'],
'A': ['A0', 'A1', 'A2', 'A3'],
'B': ['B0', 'B1', 'B2', 'B3']})
right = pd.DataFrame({'key1': ['K0', 'K1', 'K1', 'K2'],
'key2': ['K0', 'K0', 'K0', 'K0'],
'C': ['C0', 'C1', 'C2', 'C3'],
'D': ['D0', 'D1', 'D2', 'D3']})
result=pd.merge(左,右,开=['key1','key2'](
结果:
A B key1 key2 C D
0 A0 B0 K0 K0 C0 D0
1 A2 B2 K1 K0 C1 D1
2 A2 B2 K1 K0 C2 D2
None
有没有一种方法可以让我从"右"数据帧中只选择列"C",从左数据帧中选择列"a"?例如,我希望我的结果是:
A key1 key2 C
0 A0 K0 K0 C0
1 A2 K1 K0 C1
2 A2 K1 K0 C2
None
当然,首先过滤必要的列+用于联接的列:
result = pd.merge(left[['A','key1', 'key2']],
right[['C','key1', 'key2']],
on=['key1', 'key2'])
或者:
keys = ['key1', 'key2']
result = pd.merge(left[['A'] + keys], right[['C'] + keys], on=keys)
mergeDF = pd.merge(left['key1','key2','A'], right[['key1','key2','C']], on=['key1', 'key2'])