How to replace values in dataframe by choosing elements from list at random?

Question

I have a dataframe with 1's and 0's which looks like:

Index Variable_1 Variable_2 Variable_3
A     1          0          1
B     0          1          1
C     0          0          1

I also have a list which looks like: {'X','Y','Z'}

I want to replace all '1's in the dataframe with values from the list at random. So the output could look like:

Index Variable_1 Variable_2 Variable_3
A     Y          0          X
B     0          Z          Y
C     0          0          Z

How can I achieve this?

A.B · Accepted Answer · 2020-10-14 15:45:46Z

1

you can use np.where and random.choice as

import random

yourlist = ['X','Y','Z']
df = df.where(df == 1, random.choice(yourlist))

You can also use .replace as

df = df.replace(1, random.choice(yourlist))

Update: you are right that we have random.choice same for every replacement, it isnt evaluated for all element?

can you try this and see how it works

 df = df.update(np.random.choice(yourlist, size=df.shape), filter_func=lambda x: x==1)

edited Oct 14, 2020 at 15:45

answered Oct 12, 2020 at 17:23

A.B

20.5k3 gold badges43 silver badges74 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Alberto Castillo Over a year ago

The problem with your code is that random.choice only pick one letter for all replaced rows

A.B Over a year ago

@AlbertoCastillo are you sure ? it is supposed to take random selections

Alberto Castillo Over a year ago

Yep... I ran your code and all 1 numbers has been replaced by only one letter, random, but just one letter, f.i. 1 by 'X' or 1 by 'Y'. And I think it makes sense due to replace and where takes all rows = 1 and replace with any letter, all in one step, it's not like iteration... but your answer has been marked as good so I suppose it works for @Thelonius. Cheers!

Thelonious Monk Over a year ago

@Alberto Castillo Indeed, the issue you described is true. I did not check it properly earlier. The above code replaces each '1' with the same random element from the list

A.B Over a year ago

I have updated the answer, let me know if it works?

|

Collectives™ on Stack Overflow

How to replace values in dataframe by choosing elements from list at random?

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related