在 pandas python 中填充来自其他数据帧的数据帧值

Question

I have 2 dataframes df1 and df2. df1 is filled with values and df2 is empty.

df1 and df2, as it can be seen, both dataframes's index and columns will always be same, just difference is df1 doesn't contain duplicate values of columns and indexes but df2 does contain.

How to fill values in df2 from df1, so that it also considers the combination of index and columns?

df1 = pd.DataFrame({'Ind':pd.Series([1,2,3,4]),1:pd.Series([1,0.2,0.2,0.8])
                    ,2:pd.Series([0.2,1,0.2,0.8]),3:pd.Series([0.2,0.2,1,0.8])
                    ,4:pd.Series([0.8,0.8,0.8,1])})
df1 = df1.set_index(['Ind'])

df2 = pd.DataFrame(columns = [1,1,2,2,3,4], index=[1,1,2,2,3,4])

Answer 1

IIUC, you want to update :

df2.update(df1)
print(df2)

     1    1    2    2    3    4
1  1.0  1.0  0.2  0.2  0.2  0.8
1  1.0  1.0  0.2  0.2  0.2  0.8
2  0.2  0.2  1.0  1.0  0.2  0.8
2  0.2  0.2  1.0  1.0  0.2  0.8
3  0.2  0.2  0.2  0.2  1.0  0.8
4  0.8  0.8  0.8  0.8  0.8  1.0