Dividing column values with value in the column based on a condition

Question

How I divide column values with one of the values in the column based on a value in other column. So if I have value 2015 in the column A then all the values in column B should be divided with the value in the row with 2015 in A.

df = pd.DataFrame({"A" : (2014, 2015, 2016), "B" : (100, 200, 300)})
???
result = pd.DataFrame({"A" : (2014, 2015, 2016), "B" : (0.5, 1, 1.5)})

Answer 1

df['B'] =  df['B']/df['A']

It works exacly how you need I think.