Dataframe: if value in first column is in a list of strings, replace second column with value

Question

I am trying to implement the following logic on a python dataframe.

If the string value in Column A is in a list that I pre-designated, then replace Column B with the value in Column A. Otherwise, leave the value in column B as is.

The closest I can get right now is a wonky np.where statement that isn't quite what I want and errors out. Please see below.

Any help is greatly appreciated

Pandas or python? Also rather write out the code than take a screenshot. — tread
– tread, Commented Nov 10, 2017 at 1:55
You mean a Pandas DataFrame? Try indexing using pandas.DataFrame.isin — user2047399
– user2047399, Commented Nov 10, 2017 at 2:12
Please add code and data as text (using code formatting), not images. Images: A) don't allow us to copy-&-paste the code/errors/data for testing; B) don't permit searching based on the code/error/data contents; and many more reasons. Images should only be used, in addition to text in code format, if having the image adds something significant that is not conveyed by just the text code/error/data. — double-beep
– double-beep, Commented May 3, 2019 at 7:55

WiLL_K · Accepted Answer · 2017-11-10 13:24:07Z

1

There are a lot of way in which this can be done. One way and probably the easiest way would be

column_to_list = df['A'].tolist()
for index, value in enumerate(column_to_list):
    if value in Other_list:
        df.iloc['B'][index] = value        
    else:
        pass

If this meets you expectation let us know and please never post Photo of codes

answered Nov 10, 2017 at 13:24

WiLL_K

5931 gold badge5 silver badges22 bronze badges

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

2 Comments

WiLL_K Over a year ago

Replace Other_list with your pre-designated list.

WiLL_K Over a year ago

@PineNuts0 If it solved your problem please accept the answer. In case it didn't let us know so that we can provide better answers

Collectives™ on Stack Overflow

Dataframe: if value in first column is in a list of strings, replace second column with value

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related