Deleting A Line From A File In Python

I'm trying to delete a specific line that contains a specific string. I've a file called numbers.txt with the following content: peter tom tom1 yan What I want to delete is

Solution 1:

change the line:

if not "tom"in line:

to:

if"tom" != line.strip():

Solution 2:

That's because

if not "tom"in line

checks, whether tom is not a substring of the current line. But in tom1, tomis a substring. Thus, it is deleted.

You probably could want one of the following:

if not "tom\n"==line # checks for complete (un)identityif"tom\n" != line # checks for complete (un)identity, classical wayif not "tom"==line.strip() # first removes surrounding whitespace from `line`

Solution 3:

Just for fun, here's a two-liner to do it.

lines = filter(lambda x:x[0:-1]!="tom", open("names.txt", "r"))
open("names.txt", "w").write("".join(lines))

Challenge: someone post a one-liner for this.

You could also use the fileinput module to get arguably the most readable result:

import fileinput
for l in fileinput.input("names.txt", inplace=1):
    if l != "tom\n": print l[:-1]

Solution 4:

You can use regex.

import re
if not re.match("^tom$", line):
    output.append(line)

The $ means the end of the string.

Solution 5:

I'm new in programing and python (a few months)... this is my solution:

import fileinput

c = 0# counterfor line in fileinput.input("korrer.csv", inplace=True, mode="rb"):
    # the line I want to deleteif c == 3: 
        c += 1passelse:
        line = line.replace("\n", "")
        print line
        c +=1

I'm sure there is a simpler way, just it's an idea. (my English it's not very good looking!!)