Replace list based on column condition

Asked Mar 03 '19 at 19:54

Active Mar 03 '19 at 19:54

Viewed 19 times

I want to edit a row in in my dataframe such as:

index columnA ColumnB
0     1       [a, b]
1     3       [c, b]
2     4       [a, b]
3     6       [d, a, b]

Lets say I want to replace the [c, b] with [q, y] where the columnA is value 3. How would I go about doing that. I tried the following:

df.at[df['columnA'] == 3, 'ColumnB'] = [q, y]

Both are columns and I would like to edit the row based on the columnA value and not the index.

asked Mar 03 '19 at 19:54

Bada

My answer here could help: https://stackoverflow.com/a/54399996/4909087 – cs95 Mar 03 '19 at 19:59
@coldspeed but those only work by index right? – Bada Mar 03 '19 at 20:09
1

So you can use `df.at[(df['columnA'] == 3).idxmax(), 'ColumnB'] = ['q', 'y']` – cs95 Mar 03 '19 at 20:11
Thank you, idxmax() seems to make the difference – Bada Mar 03 '19 at 20:39
Sure, no problem. Please consider upvoting [my answer](https://stackoverflow.com/a/54399996/4909087) if it was helpful :-) – cs95 Mar 03 '19 at 20:44

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