New to python, need help on Question 2

[LalehT]

Hi,
could you please explain what does this piece of code do? why should we use Boolean masking?
x = max(df['Gold'] - df['Gold.1'])
ans = df[(df['Gold'] - df['Gold.1']) == x].index.tolist()

and why doesn't something like this work?
ans = df[max(df['Gold']-df['Gold.1'])].index.tolist()

and what does this do?
.index.tolist()

Thanks in advance.

[Villan-98]

@LalehT
max(df['Gold']-df['Gold.1']) gives the maximum difference between the value of df['Gold'] and df['Gold.1'] which is 3850(4809-959) ,this implies x=3850 .
your code:
'''df[max(df['Gold']-df['Gold.1'])]''' is equivalent to '''df[3850]''' which will give the key error.