在 Python 中使用 difflib 比较两个 .txt 文件

Question

我正在尝试比较两个文本文件并输出比较文件中不匹配的第一个字符串，但由于我对 python 非常陌生，所以遇到了困难。 任何人都可以给我一个使用该模块的示例方法吗？

当我尝试类似的操作时：

result = difflib.SequenceMatcher(None, testFile, comparisonFile)

我收到一条错误消息，指出“文件”类型的对象没有 len。

Answer 1

对于初学者，您需要将字符串传递给 difflib.SequenceMatcher，而不是文件：

# Like so
difflib.SequenceMatcher(None, str1, str2)

# Or just read the files in
difflib.SequenceMatcher(None, file1.read(), file2.read())

这将修复您的错误。

要获取第一个不匹配的字符串，请参阅 difflib 文档。

Answer 2

这是使用 Python difflib 比较两个文件内容的快速示例...

import difflib

file1 = "myFile1.txt"
file2 = "myFile2.txt"

diff = difflib.ndiff(open(file1).readlines(),open(file2).readlines())
print ''.join(diff),

Answer 3

您确定这两个文件都存在吗？

刚刚测试了一下，我得到了完美的结果。

为了获得结果，我使用类似的方法：

import difflib

diff=difflib.ndiff(open(testFile).readlines(), open(comparisonFile).readlines())

try:
    while 1:
        print diff.next(),
except:
    pass

每行的第一个字符指示它们是否不同：
例如：“+”表示已添加以下行等。

Answer 4

听起来您可能根本不需要 difflib。 如果您要逐行比较，请尝试以下操作：

test_lines = open("test.txt").readlines()
correct_lines = open("correct.txt").readlines()

for test, correct in zip(test_lines, correct_lines):
    if test != correct:
        print "Oh no! Expected %r; got %r." % (correct, test)
        break
else:
    len_diff = len(test_lines) - len(correct_lines)
    if len_diff > 0:
        print "Test file had too much data."
    elif len_diff < 0:
        print "Test file had too little data."
    else:
        print "Everything was correct!"

Answer 5

另一种更简单的方法来检查两个文本文件是否逐行相同。 试试看。

fname1 = 'text1.txt'
fname2 = 'text2.txt'

f1 = open(fname1)
f2 = open(fname2)

lines1 = f1.readlines()
lines2 = f2.readlines()
i = 0
f1.seek(0)
f2.seek(0)
for line1 in f1:
    if lines1[i] != lines2[i]:
        print(lines1[i])
        exit(0)
    i = i+1

print("both are equal")

f1.close()
f2.close()

否则，你可以使用 python 中的 filecmp 预定义文件。

import filecmp

fname1 = 'text1.txt'
fname2 = 'text2.txt'

print(filecmp.cmp(fname1, fname2))

:)

Answer 6

# -*- coding: utf-8 -*-
"""
   

"""

def compare_lines_in_files(file1_path, file2_path):
    try:
        with open(file1_path, 'r', encoding='utf-8') as file1, open(file2_path, 'r', encoding='utf-8') as file2:
            lines_file1 = file1.readlines()
            lines_file2 = file2.readlines()

            mismatched_lines = []

            # Compare each line in file1 to all lines in file2
            for line_num, line1 in enumerate(lines_file1, start=1):
                line1 = line1.strip()  # Remove leading/trailing whitespace
                found_match = False

                for line_num2, line2 in enumerate(lines_file2, start=1):
                    line2 = line2.strip()  # Remove leading/trailing whitespace

                    # Perform a case-insensitive comparison
                    if line1.lower() == line2.lower():
                        found_match = True
                        break

                if not found_match:
                    mismatched_lines.append(f"Line {line_num} in File 1: '{line1}' has no match in File 2")

            # Compare each line in file2 to all lines in file1 (vice versa)
            for line_num2, line2 in enumerate(lines_file2, start=1):
                line2 = line2.strip()  # Remove leading/trailing whitespace
                found_match = False

                for line_num, line1 in enumerate(lines_file1, start=1):
                    line1 = line1.strip()  # Remove leading/trailing whitespace

                    # Perform a case-insensitive comparison
                    if line2.lower() == line1.lower():
                        found_match = True
                        break

                if not found_match:
                    mismatched_lines.append(f"Line {line_num2} in File 2: '{line2}' has no match in File 1")

            return mismatched_lines

    except FileNotFoundError:
        print("One or both files not found.")
        return []

# Paths to the two text files you want to compare
file1_path = r'C:\Python Space\T1.txt'
file2_path = r'C:\Python Space\T2.txt'

mismatched_lines = compare_lines_in_files(file1_path, file2_path)

if mismatched_lines:
    print("Differences between the files:")
    for line in mismatched_lines:
        print(line)
else:
    print("No differences found between the files.")