difflib 序列匹配器缺少公共子串

Question

在尝试查找两个字符串之间的公共子串时，SequenceMatcher 没有 return 所有预期的公共子串。

s1 = '++%2F%2F+Prints+%22Hello%2C+World%22+to+the+terminal+window.%0A++++++++System.out.pr%29%3B%0A++++%7D%0A%7D%0ASample+program%0Apublic+static+voclass+id+main%28String%5B%5D+args%29+'
s2 = 'gs%29+%7B%0A++++++++%2F'
# The common substring are '+%', '%0A++++++++', '%s' and 'gs%29+'
# but 'gs%29+' is not matched.

import difflib as d

seqmatch = d.SequenceMatcher(None,s1,s2)
matches = seqmatch.get_matching_blocks()

for match in matches:
    apos, bpos, matchlen = match
    print(s1[apos:apos+matchlen])

输出：

+%
%0A++++++++
%2

"gs%29+"是s1和s2之间的公共子串，但SequenceMatcher找不到。

我是不是漏掉了什么？

谢谢

Answer 1

可能是垃圾字符把算法给搞糊涂了。我在 SequenceMatcher()

中为 isjunk 添加了一个 lambda 函数

s1 = '++%2F%2F+Prints+%22Hello%2C+World%22+to+the+terminal+window.%0A++++++++System.out.pr%29%3B%0A++++%7D%0A%7D%0ASample+program%0Apublic+static+voclass+id+main%28String%5B%5D+args%29+'
s2 = 'gs%29+%7B%0A++++++++%2F'
# The expected substring is 'gs%29+'

import difflib as d

seqmatch = d.SequenceMatcher(lambda x: x in "+", s1, s2)
matches = seqmatch.get_matching_blocks()

for match in matches:
    apos, bpos, matchlen = match
    print(s1[apos:apos+matchlen])

现在输出

gs%29+

difflib 序列匹配器缺少公共子串

difflib sequence matcher missing common substrings

python

difflib

sequencematcher