Python 正则表达式错误字符范围. [英] Python regex bad character range.

问题描述

我使用以下正则表达式来匹配不同的日期模式.它在 regex101.com 中运行良好.但是当我导入到 python 时，我得到了bad character range"异常.

 pattern = ur"((?:\b((?:(january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug)|september|set|sep|october|oct|november|nov|december|dec)['\s\.]{0,4}(?:\d{4}|\d{2})|(?:一月|一月|二月|二月|三月|三月|四月|四月|五月|六月|六月|七月|七月|八月|八月|九月|集|九月|十月|十月|十一月|十一月|十二月|十二月(?:0[1-9]|[1-3][0-9]|[0-9])/(?:0[1-9]|[1-3][0-9])/(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0]-9]))|((?:0[1-9]|1[0-2]|[1-9])\s{0,3}[-/']{1,3}[\s-/']{0,3}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]]|[0-1][0-9])))))(?:(?![\r\n])\s){0,4})[-/–to]{0,2}(?:(?![\r\n])\s){0,4}(((?:january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug|september|set|sep|october|oct|november|nov|december|dec)[-'\s\.]{0,4}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))|((?:0[1-9]|[1-3][0-9]|[1-9])/(?:0[1-9]|[1-3][0-9])/(?:(19)[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))|(((?:0[1-9]|1[0-2]|[1-9])\s{0,3}[-/']{1,3}[\s-/']{0,3}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9]))))))"https://regex101.com/r/rU3cE9/1

解决方案

问题主要是因为[\s-/']字符类中存在连字符，因此Python将其解释为字符间隔(如在 [az] 中).我建议您将连字符放在字符类 [-\s/'] 中的第一个或最后一个位置或将其转义，以防止歧义.

<预><代码>>>>reg = re.compile(ur"((?:\b((?:(一月|一月|二月|二月|三月|三月|四月|四月|五月|六月|六月|七月|七月|八月|八月|九月|set|sep|october|oct|november|nov|december|dec)['\s\.]{0,4}(?:\d{4}|\d{2})|(?:january|一月|二月|二月|三月|三月|四月|四月|五月|六月|六月|七月|七月|八月|八月|九月|集|九月|十月|十月|十一月|十一月|十二月|十二月)|((?:0[1-9]|[1-3][0-9]|[0-9])/(?:0[1-9]|[1-3][0-9])/(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9]]))|((?:0[1-9]|1[0-2]|[1-9])\s{0,3}[-/']{1,3}[-\s/']{0,3}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))))(?:(?![\r\n])\s){0,4})[-/to-]{0,2}(?:(?![\r\n])\s){0,4}(((?:january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug|september|set|sep|october|oct|november|nov|december|dec)[-'\s\.]{0,4}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))|((?:0[1-9]|[1-3][0-9]|[1-9])/(?:0[1-9]|[1-3][0-9])/(?:(19[7]-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))|((?:0[1-9]|1[0-2]|[1-9])\s{0,3}[-/']{1,3}[-\s/']{0,3}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))))))")>>>

I am using the following regex to match different patterns of dates. it works fine in regex101.com. But when I import to python i am getting "bad character range" exception.

  pattern = ur"((?:\b((?:(january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug|september|set|sep|october|oct|november|nov|december|dec)['\s\.]{0,4}(?:\d{4}|\d{2})|(?:january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug|september|set|sep|october|oct|november|nov|december|dec)|((?:0[1-9]|[1-3][0-9]|[0-9])/(?:0[1-9]|[1-3][0-9])/(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9]))|((?:0[1-9]|1[0-2]|[1-9])\s{0,3}[-/']{1,3}[\s-/']{0,3}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))))(?:(?![\r\n])\s){0,4})[-/–to]{0,2}(?:(?![\r\n])\s){0,4}(((?:january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug|september|set|sep|october|oct|november|nov|december|dec)[-'\s\.]{0,4}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))|((?:0[1-9]|[1-3][0-9]|[1-9])/(?:0[1-9]|[1-3][0-9])/(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))|((?:0[1-9]|1[0-2]|[1-9])\s{0,3}[-/']{1,3}[\s-/']{0,3}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9]))))))"

  https://regex101.com/r/rU3cE9/1

解决方案

Problem is mainly because of the hyphen present inside [\s-/'] character class, therefore Python interprets it as a character interval (like in [a-z]). I suggest you to put the hyphen at the first or at the last position inside the character class [-\s/'] or escape it, to prevent ambiguity.

>>> reg = re.compile(ur"((?:\b((?:(january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug|september|set|sep|october|oct|november|nov|december|dec)['\s\.]{0,4}(?:\d{4}|\d{2})|(?:january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug|september|set|sep|october|oct|november|nov|december|dec)|((?:0[1-9]|[1-3][0-9]|[0-9])/(?:0[1-9]|[1-3][0-9])/(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9]))|((?:0[1-9]|1[0-2]|[1-9])\s{0,3}[-/']{1,3}[-\s/']{0,3}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))))(?:(?![\r\n])\s){0,4})[-/to–]{0,2}(?:(?![\r\n])\s){0,4}(((?:january|jan|february|feb|march|mar|april|apr|may|jun|june|july|jul|august|aug|september|set|sep|october|oct|november|nov|december|dec)[-'\s\.]{0,4}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))|((?:0[1-9]|[1-3][0-9]|[1-9])/(?:0[1-9]|[1-3][0-9])/(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9])))|((?:0[1-9]|1[0-2]|[1-9])\s{0,3}[-/']{1,3}[-\s/']{0,3}(?:(19[7-9][0-9])|(20[0-1][0-9])|([7-9][0-9]|[0-1][0-9]))))))")
>>> 

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