set value only according column name in dataframe

Question

    max_speed  shield  new
1   1          2       3
2   4          5       6

I got this dataframe, and I want to assign a value according to some column names. like this df.loc[df['max_speed']==1, df['shield']==2, new] = 10 then I will get the new dataframe:

    max_speed  shield  new
 1  1          2       10
 2  4          5       6

Anyone know how to do it?

sudonym · Answer 1 · 2018-06-21T07:04:37.043

2

you are pretty close.

df.loc[(df.max_speed == 1) & (df.shield == 2), "new"] = 10

For further reading, see here.

edited Jun 21 '18 at 07:04

answered Jun 21 '18 at 07:03

sudonym

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coldspeed, it's 8 after midnight, you never sleep? :) – sudonym Jun 21 '18 at 07:07
1

Sleep is for the weak – cs95 Jun 21 '18 at 07:08
1

It works! I got one more question, I can not find the method you provided in the DataFrame.loc document. Hwo do you know this method works? – Lilian417 Jun 21 '18 at 07:09

score 2 · Answer 2 · answered Jun 21 '18 at 07:05

2

Alternative with where if you want to change the value if doesnt fullfill your conditions:

df['new'] = np.where((df['max_speed']==1) & (df['shield']==2) , 10, df['new'])

answered Jun 21 '18 at 07:05

Joe

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set value only according column name in dataframe

2 Answers2