pandas - can't merge on index. tried using join, merge,

Question

Tried combining the to dataframes on index using the methods below

df_result = pd.concat([df1,df2])

pd.merge(df2, df1, left_index=True,right_index=True)

df2.join(df1)

But it's not working, nothing is merged.

Is it because I converted the series to a dataframe df1. Do I have to set index somehow on the df1 ?

df1

    signal
6        1
7       -1
8       -1
9       -1
10      -1
11       1

df2

   my_id  
0  638BB   
1  639AA   
2  sddsf   
3  233dd  
4  rere3   
5  erre3  
6  jjk54   
7  sdg88 
8  sdfd2  
9  sdfd3

expected result = df_result

   my_id  signal
0  638BB   NaN
1  639AA   NaN
2  sddsf   NaN
3  233dd   NaN
4  rere3   NaN
5  erre3   NaN
6  jjk54    1
7  sdg88   -1
8  sdfd2   -1
9  sdfdf.  -1

Answer 1

等待大神答复