python 比较和处理文本之间的差异

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• difflib是Python标准库中的一个模块，用于比较和处理文本之间的差异。它提供了一些函数和类，可以用于生成差异报告、计算相似度、查找最长公共子序列等操作。
  安装内置库 无需安装常见用法1：比较差异
  1. import difflib
     
  2. ​
     
  3. text1 = "hello world"
     
  4. text2 = "hello there"
     
  5. ​
     
  6. diff = difflib.ndiff(text1, text2)
     
  7. print('\n'.join(diff))

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  常见用法2：比较文件的差异
  1. import difflib
     
  2. ​
     
  3. with open('file1.txt') as file1, open('file2.txt') as file2:
     
  4.     diff = difflib.ndiff(file1.readlines(), file2.readlines())
     
  5.     print('\n'.join(diff))

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  常见用法3：比较列表的差异
  1. import difflib
     
  2. ​
     
  3. list1 = ['apple', 'banana', 'cherry']
     
  4. list2 = ['apple', 'banana', 'kiwi']
     
  5. ​
     
  6. diff = difflib.ndiff(list1, list2)
     
  7. print('\n'.join(diff))

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  常见用法4：比较字符串相似度
  1. import difflib
     
  2. ​
     
  3. text1 = "hello world"
     
  4. text2 = "hello there"
     
  5. ​
     
  6. similarity = difflib.SequenceMatcher(None, text1, text2).ratio()
     
  7. print(similarity)

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  输出，相似度 百分之63.6%0.6363636363636364常见用法5：获取两个字符串的相似块：
  1. import difflib
     
  2. 
     
  3. text1 = "hello world"
     
  4. text2 = "hello there"
     
  5. 
     
  6. blocks = difflib.SequenceMatcher(None, text1, text2).get_matching_blocks()
     
  7. print(blocks)

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  输出[Match(a=0, b=0, size=6), Match(a=8, b=9, size=1), Match(a=11, b=11, size=0)]
• 常见用法6：获取两个字符串的最长公共子序列
  1. import difflib
     
  2. text1 = "hello world"
     
  3. text2 = "hello there"
     
  4. 
     
  5. lcs = difflib.SequenceMatcher(None, text1, text2).find_longest_match(0, len(text1), 0, len(text2))
     
  6. print(lcs)

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  输出Match(a=0, b=0, size=6)
  1. import difflib
     
  2. 
     
  3. text1 = "hello world"
     
  4. text2 = "hello there"
     
  5. 
     
  6. lcs = difflib.SequenceMatcher(None, text1, text2).find_longest_match(0, len(text1), 0, len(text2))
     
  7. print(text1[lcs.a: lcs.a + lcs.size])

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  输出hello 常见用法7：比较两个字符串，并返回上下文差异
  1. import difflib
     
  2. ​
     
  3. text1 = "hello world"
     
  4. text2 = "hello there"
     
  5. ​
     
  6. diff = difflib.context_diff(text1, text2)
     
  7. print('\n'.join(diff)
     

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