Replace the 3's column as shown in the picture into an increment counter in python

Question

i want to replace the 3's column as shown in the picture into an increment counter. I tried using replace but the output is not what i expected

picture data

Here is my code:

lines = open('test1.txt', 'r').readlines()[2:]

count=0

for line in lines:

count+=1

line=line.replace(line.split("  ")[1],str(count))

print(line.rstrip())

Answer 1

You're always going to replace the final column, right? No need to use replace. Just use split and keep the first one.

count = 0
lines = open('test1.txt', 'r')
for line in lines:
    if not line[0].isdigit():
        continue
    parts = line.split()
    print(parts[0], count)
    count += 1

Answer 2

lines = open('test.txt', 'r').readlines()

count = 0;

with open('test.txt', 'w') as f:

    for x in lines:
        
        count+=1
        
        line = x.split(" ")
        f.write(line[0] + " " + str(count) + "\n")