I don't understand the difference between these two lines of code and why they return different results

Question

I don't understand the difference between these two lines of code, and why they return different results when I use brackets.

df["Winner fav"] = (df["WPts"] - df["LPts"]).apply(lambda x: 1 if x>0 else 0)

df2["Winner fav"] = df2["WPts"] - df2["LPts"].apply(lambda x: 1 if x>0 else 0)

Answer 1

It's an operator precedence issue. The first one,

df["Winner fav"] = (df["WPts"] - df["LPts"]).apply(lambda x: 1 if x>0 else 0)

applies the lambda function on the difference of df["WPts"] - df["LPts"] .

The second one,

df2["Winner fav"] = df2["WPts"] - df2["LPts"].apply(lambda x: 1 if x>0 else 0)

first applies the lambda on the value of df2["LPts"] and then subtracts 1 or 0 from df2["WPts"]