How to count how many lines in a file are the same?

Question

I have a text document in the format of:

-1+1
-1-1
+1+1
-1-1
+1-1
...

I want to have a program that counts how many lines have -1+1 lines and +1-1 lines. The program would then just need to return the value of how many lines are like this.

I have written the code:

f1 = open("results.txt", "r")
fileOne = f1.readlines()
f1.close()

x = 0
for i in fileOne:
    if i == '-1+1':
        x += 1
    elif i == '+1-1':
        x += 1
    else:
        continue

print x

But for some reason, it always returns 0 and I have no idea why.

Answer 1

Use collections.Counter instead:

import collections

with open('results.txt') as infile:
    counts = collections.Counter(l.strip() for l in infile)
for line, count in counts.most_common():
    print line, count

Most of all, remove whitespace (the newline specifically, but any other spaces or tabs might interfere too) when counting your lines.

Answer 2

The .readlines() leaves the \n in the lines, that's why they don't match.