我在尝试寻找整数序列中的模式。我在this link找到了KNUTH-MORRIS-PRATT(KMP)。你知道吗
我给函数提供了一个“模式”来在“文本”中查找,但是KMP的输出 函数是一个对象。我需要文本中模式实例的索引。我试着通过键入dot并按tab键来检查对象的属性,但什么都没有。如何获取索引?你知道吗
编辑
代码:
> # Knuth-Morris-Pratt string matching
> # David Eppstein, UC Irvine, 1 Mar 2002
>
> from __future__ import generators
>
> def KnuthMorrisPratt(text, pattern):
>
> '''Yields all starting positions of copies of the pattern in the text. Calling conventions are similar to string.find, but its
> arguments can be lists or iterators, not just strings, it returns all
> matches, not just the first one, and it does not need the whole text
> in memory at once. Whenever it yields, it will have read the text
> exactly up to and including the match that caused the yield.'''
>
> # allow indexing into pattern and protect against change during yield
> pattern = list(pattern)
>
> # build table of shift amounts
> shifts = [1] * (len(pattern) + 1)
> shift = 1
> for pos in range(len(pattern)):
> while shift <= pos and pattern[pos] != pattern[pos-shift]:
> shift += shifts[pos-shift]
> shifts[pos+1] = shift
>
> # do the actual search
> startPos = 0
> matchLen = 0
> for c in text:
> while matchLen == len(pattern) or \
> matchLen >= 0 and pattern[matchLen] != c:
> startPos += shifts[matchLen]
> matchLen -= shifts[matchLen]
> matchLen += 1
> if matchLen == len(pattern):
> yield startPos
Sample Text: [1, 2, 2, 3, 3, 2, 4, 5, 2, 2, 3, 2]
Sample Pattern: [2, 2, 3]
Sample output: [1, 8]
您没有从函数返回任何内容,需要使用
comprehension
循环遍历迭代器以获取索引。重写如下:相关问题 更多 >
编程相关推荐