How to filter negative and positive returns by weekday in Python?

Question

I need to either create a for loop or a list comprehension to filter out negative returns and positive returns by weekday.

I’m using a csv file of a stock ticker from yahoo finance. There is a column “weekday” and a column for “return”. What basic loop or list comprehension can I use?

I am using pandas but can do something without and not using numpy.

Answer 1

Suppose your df looks like this

  weekday   return
0       M        1
1       W       -3
2       F        4
3       T        5
4       W       -3
5       F       -2
6       M       -4

you can filter by weekday and negative return by

df[(df['weekday'] == 'M') & (df['return'] < 0)]