replacing a character in a line of string

Question

I have a .txt file with 20 lines. Each line carrying 10 zeroes separated by comma.

0,0,0,0,0,0,0,0,0,0

I want to replace every fifth 0 with 1 in each line. I tried .replace function but I know there must be some easy way in python

Answer 1

You can split the text string with the below command.

text_string="0,0,0,0,0,0,0,0,0,0"
string_list= text_string.split(",")

Then you can replace every fifth element in the list string_list using insert command.

for i in range(4,len(string_list),5):
    string_list.insert(i,"1")

After this join the elements of the list using join method

output = "".join([str(i)+"," for i in string_list])

The output for this will be :

'0,0,0,0,1,0,0,0,0,1,0,0,'

This is one way of doing

Answer 2

If text in this File follows some rule, you can parse it as CSV file, and change every fifth index and rewrite it to a new file.

But if you want to modify the existing text file, like replace the character then you can use seek refer to How to modify a text file?