如何在python中比较两个文件并打印不匹配的行号？

Question

我有两个包含相同行数的文件。

"file1.txt" contains following lines:

 Attitude is a little thing that makes a big difference
 The only disability in life is a bad attitude
 Abundance is, in large part, an attitude
 Smile when it hurts most

"file2.txt" contains:

 Attitude is a little thing that makes a big difference
 Everyone has his burden. What counts is how you carry it
 Abundance is, in large part, an attitude
 A positive attitude may not solve all your problems  

我想逐行比较两个文件，如果我想比较两个文件之间的任何行不匹配

 print "mismatch in line no: 2"
 print "mismatch in line no: 4"   #in this case lineno: 2 and lineno: 4 varies from second file

我试过了。但我只能打印 file1 中与 file2 中的行不同的行。无法打印不匹配行的行号。??

 My code:
 with open("file1.txt") as f1:
    lineset = set(f1)
 with open("file2.txt") as f2:
    lineset.difference_update(f2)
    for line in lineset:
        print line

Answer 1

使用itertools.izip并enumerate ：

import itertools

with open('file1.txt') as f1, open('file2.txt') as f2:
    for lineno, (line1, line2) in enumerate(itertools.izip(f1, f2), 1):
        if line1 != line2:
            print 'mismatch in line no:', lineno

Answer 2

如果：

with open("file1.txt") as f1:
    with open("file2.txt") as f2:
        for idx, (lineA, lineB) in enumerate(zip(f1, f2)):
            if lineA != lineB:
                print 'mismatch in line no: {0}'.format(idx)

或者，如果行数不同，您可以尝试izip_longest

import itertools

with open("file1.txt") as f1:
    with open("file2.txt") as f2:
        for idx, (lineA, lineB) in enumerate(itertools.izip_longest(f1, f2)):
            if lineA != lineB:
                print 'mismatch in line no: {0}'.format(idx)

Answer 3

您也许可以使用difflib模块。 这是一个使用其difflib.Differ类的简单示例：

import difflib
import sys

with open('file1.txt') as file1, open('file2.txt') as file2:
    line_formatter = '{:3d}  {}'.format
    file1_lines = [line_formatter(i, line) for i, line in enumerate(file1, 1)]
    file2_lines = [line_formatter(i, line) for i, line in enumerate(file2, 1)]
    results = difflib.Differ().compare(file1_lines, file2_lines)
    sys.stdout.writelines(results)

输出：

    1  Attitude is a little thing that makes a big difference
-   2  The only disability in life is a bad attitude
+   2  Everyone has his burden. What counts is how you carry it
    3  Abundance is, in large part, an attitude
-   4  Smile when it hurts most
+   4  A positive attitude may not solve all your problems

第一列中的减号和加号字符表示以典型diff实用程序样式替换的行。 没有任何指示符意味着这两个文件中的行是相同的——如果你愿意，你可以禁止打印那些，但为了保持示例简单， compare()方法创建的所有内容都被打印。

作为参考，以下是并排显示的两个文件的内容，并显示了行号：

1  Attitude is a little thing that makes a big difference    Attitude is a little thing that makes a big difference
2  The only disability in life is a bad attitude             Everyone has his burden. What counts is how you carry it
3  Abundance is, in large part, an attitude                  Abundance is, in large part, an attitude
4  Smile when it hurts most                                  A positive attitude may not solve all your problems

Answer 4

import itertools

with open('file1.txt') as f1, open('file2.txt') as f2:
    for lineno, (line1, line2) in enumerate(zip(f1, f2), 1):
        if line1 != line2:
            print ('mismatch in line no:', lineno)