I have a dataframe:
id val size
1 100
2 500
3 300
i have a nested list L = [[300,20],[100,45],[500,12]]
I want to fill my dataframe with 2nd element in my sublist, corresponding to that column value.
i.e my final dataframe should look like
id val size
1 100 45
2 500 12
3 300 20
Another way using merge
In [1417]: df.merge(pd.DataFrame(L, columns=['val', 'size']), on='val')
Out[1417]:
id val size
0 1 100 45
1 2 500 12
2 3 300 20
First initialise a mapping:
In [132]: mapping = dict([[300,20],[100,45],[500,12]]); mapping
Out[132]: {100: 45, 300: 20, 500: 12}
Now, you can use either df.replace or df.map.
Option 1
Using df.replace:
In [137]: df['size'] = df.val.replace(mapping)
In [138]: df
Out[138]:
id val size
0 1 100 45
1 2 500 12
2 3 300 20
Option 2
Using df.map:
In [140]: df['size'] = df.val.map(mapping)
In [141]: df
Out[141]:
id val size
0 1 100 45
1 2 500 12
2 3 300 20
