在Python中使用公用列联接表/数据框 [英] Joining Table/DataFrames with common Column in Python
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问题描述
我有两个DataFrame:
I have two DataFrames:
df1 = ['Date_Time',
'Temp_1',
'Latitude',
'N_S',
'Longitude',
'E_W']
df2 = ['Date_Time',
'Year',
'Month',
'Day',
'Hour',
'Minute',
'Seconds']
因为您可以看到两个DataFrame都有Date_Time
作为公共列.我想通过匹配Date_Time
来加入这两个DataFrame.
As You can see both DataFrames have Date_Time
as a common column. I want to Join these two DataFrames by matching Date_Time
.
我当前的代码是:df.join(df2, on='Date_Time')
,但这给出了错误.
My current code is: df.join(df2, on='Date_Time')
, but this is giving an error.
推荐答案
You are looking for a merge
:
df1.merge(df2, on='Date_Time')
关键字与join
相同,但join
仅使用索引,请参见.
The keywords are the same as for join
, but join
uses only the index, see "Database-style DataFrame joining/merging".
这是一个简单的例子:
import pandas as pd
df1 = pd.DataFrame([[1, 2, 3]])
df2 = pd.DataFrame([[1, 7, 8],[4, 9, 9]], columns=[0, 3, 4])
In [4]: df1
Out[4]:
0 1 2
0 1 2 3
In [5]: df2
Out[5]:
0 3 4
0 1 7 8
1 4 9 9
In [6]: df1.merge(df2, on=0)
Out[6]:
0 1 2 3 4
0 1 2 3 7 8
In [7]: df1.merge(df2, on=0, how='outer')
Out[7]:
0 1 2 3 4
0 1 2 3 7 8
1 4 NaN NaN 9 9
如果您尝试加入一列,则会出现错误:
If you try and join on a column you get an error:
In [8]: df1.join(df2, on=0)
# error!
Exception: columns overlap: array([0], dtype=int64)
请参见索引" .
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