基于来自另一个数据帧的索引和列填充数据帧

Question

I am wondering if it is possible to fill an empty dataframe with a predetermined index and columns with another dataframe? Here I have 2 dataframes df1 and df2, I want to fill df2 with values from df1, but keep the shape of the df2. The columns will also not be the same order.

values1 = pd.Series(['P1','P2','P3','P4','P5'])
values2 = pd.Series([30,40,50,70,80])
values3 = pd.Series([10,20,30,40,50])
df1 = pd.DataFrame({'A':values1,'C':values2,'B':values3})
df1 = df1.set_index(['A'])

df2 = pd.DataFrame(columns = ['A','B','C','D'])
df2_a_val = pd.Series(['P1','P2','P3','P4','P5','P6','P7','P8'])
df2['A'] = df2_a_val
df2 = df2.set_index(['A'])

Answer 1

Here's a way you can do using merge :

df2 = (df2
      .merge(df1, left_index=True, right_index=True, how='left', suffixes=('','_'))
      .drop(['B','C'], 1)
      .rename(columns={'C_': 'C', 'B_': 'D'}))

      D     C     D
A                  
P1  NaN  30.0  10.0
P2  NaN  40.0  20.0
P3  NaN  50.0  30.0
P4  NaN  70.0  40.0
P5  NaN  80.0  50.0
P6  NaN   NaN   NaN
P7  NaN   NaN   NaN
P8  NaN   NaN   NaN