CODEWITHSUNDEEP
python
MY_1129
MY_1129

Reputation: 317

compare two files' contents extracting different contents in python

I have two files, file1 contains contents as

aaa

bbb

ccc

and file 2 contains contents as

ccc

ddd

eee

aaa

rrr

bbb

nnn

I would like to do like this, if file2 contains file1's line, then that line would be removed from file2. At last, file2 will be as ddd eee rrr nnn Besides, my code is 

f1 = open("test1.txt","r")
f2 = open("test2.txt","r")

    fileOne = f1.readlines()
    fileTwo = f2.readlines()
    f1.close()
    f2.close()
    outFile = open("test.txt","w")
    x = 0
    for i in fileOne:
        if i !=  fileTwo[x]:
            outFile.writelines(fileTwo[x])
        x += 1

outFile.close()

Thank you.

Upvotes: 0

Views: 4169

Answers (3)

John La Rooy
John La Rooy

Reputation: 304205

with open("f1.txt") as f1:
    s1 = set(f1)
with open("f2.txt") as f2, open("f3.txt","w") as f3:
    f3.writelines(x for x in f2 if x not in s1)

It's good practice to use a context manager to close the file (this is what the with does).

It's much more efficient to check for membership of a set than a list

If there is a possibility of extra whitespace, you should strip the lines like this

with open("f1.txt") as f1:
    s1 = set(x.strip() for x in f1)
with open("f2.txt") as f2, open("f3.txt","w") as f3:
    f3.writelines(x for x in f2 if x.strip() not in s1)

Upvotes: 4

b10hazard
b10hazard

Reputation: 7809

Using your code...

f1 = open("test1.txt","r").read()
f2 = open("test2.txt","r").read()

fileOne = f1.splitlines()
fileTwo = f2.splitlines()

# remove the dup lines
nodup_lines = [line for line in fileTwo if line not in fileOne]
# join using newline character
newFileTwo = '\n'.join(nodup_lines)

# write file
outFile = open("test.txt","w")
outFile.write(newFileTwo)
outFile.close()

Upvotes: 0

mtadd
mtadd

Reputation: 2555

Use set difference to find the differences of the two files.

f1 = open("test1.txt","r").readlines()
f2 = open("test2.txt","r").readlines()

diff = set(f2) - set(f1)
outFile = open("test.txt","w")
outFile.writelines(line for line in f2 if line in diff)

Upvotes: 0

Related Questions