Python & Pandas: How to do conditional calculation

Question

df['direction'] is the number of direction of the wind, ranging from 1-16. I want to convert it into 360-degree system. #1 direction is 90, and #2 is 67.5, they run in clockwise.

I can dodf['degree'] = 90-(df.direction-1)*22.5, but this would produce negative value, you can see the output below ]1

But I don't know how to use the conditional here, for df['degree']<0, then + 360. How can I do that?

Answer 1

df['degree'] = df['degree'].apply(lambda x: x + 360 if x < 0 else x)

Answer 2

You can use .loc for conditional indexing

df.loc[ df.degree < 0 , 'degree'] += 360