Update pandas DataFrame based on index

Question

I have the following DataFrame:

df = pd.DataFrame(index=['A','B','C'], columns=['x','y'])

     x    y
A  NaN  NaN
B  NaN  NaN
C  NaN  NaN

I need to update column 'x' based on matching the index value to the following dictionary:

my_dict = {'A': "map_1", 'B': "map_2", "c": "map_3"}

So, the end result should be;

     x     y
A  map_1  NaN
B  map_2  NaN
C  map_3  NaN

I know how to use the map function if I was comparing another column, but I need to compare the index.

Scott Boston · Accepted Answer · 2018-11-21 20:30:13Z

1

Try this:

df['x'] = df.index.map(my_dict)

Output: Note the typo on my_dict small c instead of C.

       x    y
A  map_1  NaN
B  map_2  NaN
C    NaN  NaN

answered Nov 21, 2018 at 20:30

Scott Boston

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1 Comment

yes, that's it, thanks. I didn't even thing of index.map