python-Dataframe

2023-11-16 17:16:52

创建df复制：

1.直接用df2=df1，修改df2会对df1造成影响：

In [21]: import pandas as pd

In [22]: data = {'a':[1,2,3],'b':[4,5,6]}
    ...: df1=pd.DataFrame(data)
    ...: df1
Out[22]:
   a  b
0  1  4
1  2  5
2  3  6
In [23]: df2=df1
In [24]: df2['a']=0
In [25]: df2
Out[25]:
   a  b
0  0  4
1  0  5
2  0  6
In [27]: df1
Out[27]:
   a  b
0  0  4
1  0  5
2  0  6

2.想要修改复制后的df3而不改变df1用copy（）函数：

In [28]: data = {'a':[1,2,3],'b':[4,5,6]}

In [29]: df1=pd.DataFrame(data)

In [30]: df1
Out[30]:
   a  b
0  1  4
1  2  5
2  3  6

In [31]: df3=df1.copy()

In [32]: df3
Out[32]:
   a  b
0  1  4
1  2  5
2  3  6

In [33]: df3['a']=0

In [34]: df3
Out[34]:
   a  b
0  0  4
1  0  5
2  0  6

In [35]: df1
Out[35]:
   a  b
0  1  4
1  2  5
2  3  6