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python之为替换 split () 而构建的函数的意外行为

2025年05月04日11虾米姐

我写了一个比内置函数 split() 表现更好的函数(我知道它不是惯用的 python,但我尽力了),所以当我传递这个参数时:

better_split("After  the flood   ...  all the colors came out."," .") 

我预料到这个结果:

['After', 'the', 'flood', 'all', 'the', 'colors', 'came', 'out'] 

然而,令人惊讶的是,该函数会导致(对我而言)无法理解的行为。当它到达最后两个词时,它不会抑制更多的 '',而不是将“cam”和“out”添加到结果列表中,而是将其添加到“came out”中,因此,我得到了这个:

['After', 'the', 'flood', 'all', 'the', 'colors', 'came out'] 

有更多经验的人明白为什么会这样吗? 提前感谢您的帮助!

def better_split(text,markersString): 
markers = [] 
splited = [] 
for e in markersString: 
    markers.append(e)     
for character in text: 
    if character in markers: 
        point = text.find(character) 
        if text[:point] not in character: 
            word = text[:point] 
            splited.append(word)             
            while text[point] in markers and point+1 < len(text): 
                point = point + 1 
            text = text[point:]                    
print 'final splited = ', splited 

better_split("This is a test-of the,string separation-code!", ",!-")

better_split("洪水过后……所有的颜色都出来了。",".")

split() 多重分离 如果您正在寻找具有多重分离的 split() ,请参阅: Split Strings with Multiple Delimiters?

我找到的没有 import re 的请您参考如下方法:是:

def my_split(s, seps): 
    res = [s] 
    for sep in seps: 
        s, res = res, [] 
        for seq in s: 
            res += seq.split(sep) 
    return res 

请您参考如下方法:

问题在于:

    for character in text: 

正在遍历初始字符串中的字符 — text 的原始值 — 同时:

        point = text.find(character) 

在当前字符串中搜索分隔符 — text 的当前值。因此,您的那部分功能是在您一次处理一个定界符的假设下运行的;也就是说,它假设每当您在 original text 的循环中遇到定界符时,它就是 current< 中的第一个定界符/em> 文本。

同时,这:

            while text[point] in markers and point+n < len(text): 
                point = point + 1 
            text = text[point:] 

用于一次删除多个分隔符;它的目标是删除一系列连续的定界符。这违反了上述代码一次只处理一个定界符的假设。

所以处理过程是这样的:

  [After  the flood   ...  all the colors came out.] 
handling first space after "After": 
  [After] [the flood   ...  all the colors came out.] 
handling second space after "After": 
  [After] [the] [flood   ...  all the colors came out.] 
handling space after "the": 
  [After] [the] [flood] [all the colors came out.] 
handling first space after "flood": 
  [After] [the] [flood] [all] [the colors came out.] 
handling second space after "flood": 
  [After] [the] [flood] [all] [the] [colors came out.] 
handling third space after "flood": 
  [After] [the] [flood] [all] [the] [colors] [came out.] 
handling first period of the "...": 
  [After] [the] [flood] [all] [the] [colors] [came out] [] 
-- text is now empty, no more splitting happens 

如您所见,您处理的分隔符最终不会成为您拆分的分隔符。

解决方案只是删除让您一次跳过多个定界符的逻辑——也就是说,改变这个:

            while text[point] in markers and point+n < len(text): 
                point = point + 1 
            text = text[point:] 

对此: text = text[(point + 1):]

相反,在将 word 添加到 splited 之前,确保它是非空的:

            if len(word) > 0: 
                splited.append(word)