to delete records from a file in python

Question

I have a file with 100 entries.

If a record matches in the file as provided as input by the user, I want to delete that record content from the file.

How can I do this in python?

Answer 1

with open(your_f) as f:
    lines = f.readlines()
    for ind, line in enumerate(lines): 
        if your condition: # if line contains a match 
            lines[ind] ="" # set line to empty string
    with open(your_f,"w") as f: # reopen with w to overwrite
        f.writelines(lines) # write updated lines

For example removing a line from a txt file that starts with 55:

with open("in.txt") as f:
    lines = f.readlines()
    for ind, line in enumerate(lines):
        if line.startswith("55"):
            lines[ind] = ""
    with open("in.txt","w") as f:
        f.writelines(lines)

input:

foo
bar
55 foobar
44 foo

output:

foo
bar
44 foo