i tried by using loop but it didnt get updated to the df
a=df['differnce']  
for row,value in enumerate(a):
    if(value>0):
        value==value
    else:
        value=-value
    print(value)
output came what i wanted but it does not get updated to the df o/p by loop
41.0
6.0
3.0
189.0
2.0
7.0
59.0
171.0
96.0
20.0
45.0
226.0
161.0
120.0
55.0
40.0
62.0
317.0
36.0
5.0
93.0
3.0
880.0

 
    