Python Pandas: How To Replace Values In A Dataframe Based On Another Array In Conditional Base

I have a DataFrame as follows. Both columns have Member_ID which indicates which Member_ID connected with other Member_ID col1 col2 1 3 1 4 1 5 2

Solution 1:

we can stack, map and unstack:

In [9]: d1.stack().map(d2.set_index('member_ID')['Label']).unstack()
Out[9]:
   col1 col2
0    a1   a3
1    a1   b4
2    a1   b5
3    b2   a3
4    b2   b4
5    a3   a1
6    a3   b2
7    a3   b5
8    b4   a1
9    b4   b2
10   b5   a1
11   b5   a3

Solution 2:

Or you can try this

df2.set_index('member_ID',inplace=True)
df1.apply(lambda x: x.map(df2['Label']))


   col1 col2
0    a1   a3
1    a1   b4
2    a1   b5
3    b2   a3
4    b2   b4
5    a3   a1
6    a3   b2
7    a3   b5
8    b4   a1
9    b4   b2
10   b5   a1
11   b5   a3

Solution 3:

You can use pd.DataFrame.replace using a pd.Series in a dictionary context.

d1.replace(d2.set_index('member_ID').Label)

   col1 col2
0    a1   a3
1    a1   b4
2    a1   b5
3    b2   a3
4    b2   b4
5    a3   a1
6    a3   b2
7    a3   b5
8    b4   a1
9    b4   b2
10   b5   a1
11   b5   a3