用逗号分隔字符串，但忽略括号中的逗号

Question

我试图使用python用逗号分隔字符串：

s = "year:2020,concepts:[ab553,cd779],publisher:elsevier"

但我想忽略括号[]中的任何逗号。因此，上述结果将是：

["year:2020", "concepts:[ab553,cd779]", "publisher:elsevier"]

有人对怎么做有建议吗？我试着像这样使用re.split：

params = re.split(",(?![\w\d\s])", param)

但它并没有正常运作。

Answer 1

此正则表达式适用于您的示例：

,(?=[^,]+?:)

在这里，我们使用正前瞻查找逗号，后面是非逗号和冒号字符，然后是冒号。这将正确地找到您正在搜索的<comma><key>模式。当然，如果允许键中有逗号，则必须进一步修改。

您可以查看regexr 这里。

Answer 2

result = re.split(r",(?!(?:[^,\[\]]+,)*[^,\[\]]+])", subject, 0)

,                 # Match the character “,” literally
(?!               # Assert that it is impossible to match the regex below starting at this position (negative lookahead)
   (?:               # Match the regular expression below
      [^,\[\]]          # Match any single character NOT present in the list below
                           # The literal character “,”
                           # The literal character “[”
                           # The literal character “]”
         +                 # Between one and unlimited times, as many times as possible, giving back as needed (greedy)
      ,                 # Match the character “,” literally
   )
      *                 # Between zero and unlimited times, as many times as possible, giving back as needed (greedy)
   [^,\[\]]          # Match any single character NOT present in the list below
                        # The literal character “,”
                        # The literal character “[”
                        # The literal character “]”
      +                 # Between one and unlimited times, as many times as possible, giving back as needed (greedy)
   ]                 # Match the character “]” literally
)

更新以支持括号中的两个以上项目。例如。

year:2020,concepts:[ab553,cd779],publisher:elsevier,year:2020,concepts:[ab553,cd779,xx345],publisher:elsevier

Answer 3

您可以使用用户定义的函数来解决这个问题，而不是拆分：

s = "year:2020,concepts:[ab553,cd779],publisher:elsevier"


def split_by_commas(s):
    lst = list()
    last_bracket = ''
    word = ""
    for c in s:
        if c == '[' or c == ']':
            last_bracket = c
        if c == ',' and last_bracket == ']':
            lst.append(word)
            word = ""
            continue
        elif c == ',' and last_bracket == '[':
            word += c
            continue
        elif c == ',':
            lst.append(word)
            word = ""
            continue
        word += c
    lst.append(word)
    return lst
main_lst = split_by_commas(s)

print(main_lst)

运行上述代码的结果：

['year:2020', 'concepts:[ab553,cd779]', 'publisher:elsevier']