Python difflib:突出显示内联差异？

Question

在比较相似的行时,我想突出显示同一行的差异:

a) lorem ipsum dolor sit amet
b) lorem foo ipsum dolor amet

lorem <ins>foo</ins> ipsum dolor <del>sit</del> amet

虽然difflib.HtmlDiff似乎可以执行此类内联突出显示,但它会产生非常详细的标记.

不幸的是,我无法找到另一个不按行逐行操作的类/方法.

我错过了什么吗？任何指针将不胜感激!

Answer 1

举个简单的例子:

import difflib
def show_diff(seqm):
    """Unify operations between two compared strings
seqm is a difflib.SequenceMatcher instance whose a & b are strings"""
    output= []
    for opcode, a0, a1, b0, b1 in seqm.get_opcodes():
        if opcode == 'equal':
            output.append(seqm.a[a0:a1])
        elif opcode == 'insert':
            output.append("<ins>" + seqm.b[b0:b1] + "</ins>")
        elif opcode == 'delete':
            output.append("<del>" + seqm.a[a0:a1] + "</del>")
        elif opcode == 'replace':
            raise NotImplementedError, "what to do with 'replace' opcode?"
        else:
            raise RuntimeError, "unexpected opcode"
    return ''.join(output)

>>> sm= difflib.SequenceMatcher(None, "lorem ipsum dolor sit amet", "lorem foo ipsum dolor amet")
>>> show_diff(sm)
'lorem<ins> foo</ins> ipsum dolor <del>sit </del>amet'

这适用于字符串.您应该决定如何处理"替换"操作码.

Answer 2

这是一个内联差异，灵感来自上面@tzot 的回答（也兼容 Python 3）：

def inline_diff(a, b):
    import difflib
    matcher = difflib.SequenceMatcher(None, a, b)
    def process_tag(tag, i1, i2, j1, j2):
        if tag == 'replace':
            return '{' + matcher.a[i1:i2] + ' -> ' + matcher.b[j1:j2] + '}'
        if tag == 'delete':
            return '{- ' + matcher.a[i1:i2] + '}'
        if tag == 'equal':
            return matcher.a[i1:i2]
        if tag == 'insert':
            return '{+ ' + matcher.b[j1:j2] + '}'
        assert False, "Unknown tag %r"%tag
    return ''.join(process_tag(*t) for t in matcher.get_opcodes())

它并不完美，例如，扩展“替换”操作码以识别替换的完整单词而不是几个不同的字母会很好，但这是一个很好的起点。

示例输出：

>>> a='Lorem ipsum dolor sit amet consectetur adipiscing'
>>> b='Lorem bananas ipsum cabbage sit amet adipiscing'
>>> print(inline_diff(a, b))
Lorem{+  bananas} ipsum {dolor -> cabbage} sit amet{-  consectetur} adipiscing