Python 将多列映射为键的数据帧
如何使用2个属性作为键(SeqNum和StreamId)进行合并 我试着用Python 将多列映射为键的数据帧,python,pandas,Python,Pandas,如何使用2个属性作为键(SeqNum和StreamId)进行合并 我试着用 >>> merge OrderID Symbol Stream SeqNo Timestamp 0 5000000 AXBANK 3 1158 1490250116391063414 1 5000001 AXBANK 6 1733 NaN 2 5000002 AXBANK 6 1
>>> merge
OrderID Symbol Stream SeqNo Timestamp
0 5000000 AXBANK 3 1158 1490250116391063414
1 5000001 AXBANK 6 1733 NaN
2 5000002 AXBANK 6 1244 NaN
3 5000003 AXBANK 6 1388 NaN
4 5000004 AXBANK 3 1389 1490250116392819426
但是我需要包括这两个(SeqNum SeqNo和Stream StreamId)作为键
我知道如果我在两个数据帧中重命名相同的列名并使用merge,这会很容易,但我想避免这种情况。我更愿意使用一些通用的方法,如(使用此数据帧,将这些列映射到另一个数据帧中的那些列,并获取所需的coulmns)我认为您需要:
另一个包含rename
列的解决方案:
print (pd.merge(oss, p1, left_on=['Stream','SeqNo'],
right_on=['StreamId','SeqNum'],how='left')
.drop(['StreamId','SeqNum'], axis=1))
OrderID Symbol Stream SeqNo Timestamp
0 5000000 AXBANK 3 1158 1.490250e+18
1 5000001 AXBANK 6 1733 NaN
2 5000002 AXBANK 6 1244 NaN
3 5000003 AXBANK 6 1388 NaN
4 5000004 AXBANK 3 1389 1.490250e+18
使用
join
d = {'Stream':'StreamId','SeqNo':'SeqNum'}
print (pd.merge(oss.rename(columns=d), p1, how='left'))
OrderID Symbol StreamId SeqNum Timestamp
0 5000000 AXBANK 3 1158 1.490250e+18
1 5000001 AXBANK 6 1733 NaN
2 5000002 AXBANK 6 1244 NaN
3 5000003 AXBANK 6 1388 NaN
4 5000004 AXBANK 3 1389 1.490250e+18
有没有一种方法可以保持时间戳的原样而不在我认为只有一种方法-在转换之前转换为
str
-p1.timestamp=p1.timestamp.astype(str)
。因为不可能将int
值与float
-int
一起转换为float
-请参阅
print (pd.merge(oss, p1, left_on=['Stream','SeqNo'],
right_on=['StreamId','SeqNum'],how='left')
.drop(['StreamId','SeqNum'], axis=1))
OrderID Symbol Stream SeqNo Timestamp
0 5000000 AXBANK 3 1158 1.490250e+18
1 5000001 AXBANK 6 1733 NaN
2 5000002 AXBANK 6 1244 NaN
3 5000003 AXBANK 6 1388 NaN
4 5000004 AXBANK 3 1389 1.490250e+18
d = {'Stream':'StreamId','SeqNo':'SeqNum'}
print (pd.merge(oss.rename(columns=d), p1, how='left'))
OrderID Symbol StreamId SeqNum Timestamp
0 5000000 AXBANK 3 1158 1.490250e+18
1 5000001 AXBANK 6 1733 NaN
2 5000002 AXBANK 6 1244 NaN
3 5000003 AXBANK 6 1388 NaN
4 5000004 AXBANK 3 1389 1.490250e+18
oss.join(p1.set_index(['StreamId', 'SeqNum']), on=['Stream', 'SeqNo'])
OrderID Symbol Stream SeqNo Timestamp
0 5000000 AXBANK 3 1158 1.490250e+18
1 5000001 AXBANK 6 1733 NaN
2 5000002 AXBANK 6 1244 NaN
3 5000003 AXBANK 6 1388 NaN
4 5000004 AXBANK 3 1389 1.490250e+18