Strin passing in Python class method

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Python3.6

My input string from a file is
ANG
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
My required output should be
ANG
0.0
0.0
0.0
0.0
0.0
0.0
100
0.3
But Now my input is same as output .The last two zeroes under ANG string to be replaced as 100.0 and 0.3 respectively.Please help me to get the required output.

What I have tried:

import re
class Calculate:
    def angCal(self,direction,magnitude,string):
        cnt=0
        if cnt<=6:
            f4.write(string)
            cnt+=1
        elif cnt==7:
            string=str(direction)+"\n"
            f4.write(string)
            cnt += 1
        elif cnt==8:
            string = str(magnitude) + "\n"
            f4.write(string)
            cnt += 1
        elif cnt==9:
            cnt += 1
angFlag=0
angcnt=0
f1=open("nominal.txt","r")
f4=open("pp.txt","w")
obj=Calculate()
for line in f1.readlines():
    string=line
    if re.match(r'ANG',string):
        angFlag=1
        f4.write(string)
    elif angFlag==1 and angcnt==0:

        direction=100
        magnitude=0.3
        print(string)
        obj.angCal(direction,magnitude,string)
        angFlag=0
        angcnt+=1
    elif angFlag==1 and angcnt==1:
        direction=315
        magnitude=0.4
    else:
        f4.write(string)