Change row values based on condition

Question

I have the following DataFrame:

>>> BA_df
                   'BID_price' 'ASK_price'
2017-06-01-09:30   100.00      101.50
2017-06-01-09:35   102.00      101.80
2017-06-01-09:40   101.65      101.82

What I would like to do is make both rows equal to zero if the BID_price is greater than, or equal to, the ASK_price. Otherwise, leave everything as it is. I checked out this question, which uses numpy.select(), but I'm not sure how to implement it in my case.

score 1 · Answer 1 · answered Feb 25 '19 at 16:56

1

Filter and reindex

df=df.query('BID_price<=ASK_price').reindex(df.index,fill_value=0)
df
Out[724]: 
                  BID_price  ASK_price
2017-06-01-09:30     100.00     101.50
2017-06-01-09:35       0.00       0.00
2017-06-01-09:40     101.65     101.82

Or where (mask)

df=df.where(df.BID_price<=df.ASK_price,0)
df
Out[726]: 
                  BID_price  ASK_price
2017-06-01-09:30     100.00     101.50
2017-06-01-09:35       0.00       0.00
2017-06-01-09:40     101.65     101.82

answered Feb 25 '19 at 16:56

BENY

317,841
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Thanks! Looks simple when you know how :p – scrps93 Feb 25 '19 at 16:58
@scrps93 yep . it is :-) happy coding – BENY Feb 25 '19 at 16:59

Change row values based on condition

1 Answers1