python - 使用python中的正则表达式从字符串中提取不同格式的日期

Question

我需要在 python 中使用正则表达式从字符串中提取日期，并且日期可以采用多种格式之一，并且可以在一些随机文本之间。

日期格式为:

04/20/2009; 04/20/09; 4/20/09; 4/3/09
Mar-20-2009; Mar 20, 2009; March 20, 2009; Mar. 20, 2009; Mar 20 2009;
20 Mar 2009; 20 March 2009; 20 Mar. 2009; 20 March, 2009
Mar 20th, 2009; Mar 21st, 2009; Mar 22nd, 2009
Feb 2009; Sep 2009; Oct 2010
6/2008; 12/2009
2009; 2010

提取日期后，我需要将它们升序排序。

我尝试过使用这 6 个正则表达式模式，但似乎它并不能完成所有工作。

pattern1 = r'((?:\d{1,2}[- ,./]*)(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)[a-z]*[- ,./]*\d{4})'

pattern2 = r'((?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)[a-z]*[ ,./-]*\d{1,2}[ ,./-]*\d{4})'

pattern3 = r'((?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)[a-z]*[ ,./-]*\d{4})'

pattern4 = r'((?:\d{1,2}[/-]\d{1,2}[/-](?:\d{4}|\d{2})))'

pattern5 = r'(?:(\s\d{2}[/-](?:\d{4})))'

pattern6 = r'(?:\d{4})'

Answer 1

设置一些中间变量可能很有用。

import re

short_month_names = (
    'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
    'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
)

long_month_names = (
    'January', 'February', 'March', 'April', 'May', 'June', 'July',
    'August', 'September', 'October', 'November', 'December'
)

short_month_cap = '(?:' + '|'.join(short_month_names) + ')'
long_month_cap = '(?:' + '|'.join(long_month_names) + ')'
short_num_month_cap = '(?:[1-9]|1[12])'
long_num_month_cap = '(?:0[1-9]|1[12])'

long_day_cap = '(?:0[1-9]|[12][0-9]|3[01])'
short_day_cap = '(?:[1-9]|[12][0-9]|3[01])'

long_year_cap = '(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3})'
short_year_cap = '(?:[0-9][0-9])'

ordinal_day = '(?:2?1st|2?2nd|2?3rd|[12]?[4-9]th|1[123]th|[123]0th|31st)'

formats = (
    r'(?P<month_0>{lnm}|{snm})/(?P<day_0>{ld}|{sd})/(?P<year_0>{sy}|{ly})',
    r'(?P<month_1>{sm})\-(?P<day_1>{ld}|{sd})\-(?P<year_1>{ly})',
    r'(?P<month_2>{sm}|{lm})(?:\.\s+|\s*)(?P<day_2>{ld}|{sd})(?:,\s+|\s*)(?P<year_2>{ly})',
    r'(?P<day_3>{ld}|{sd})(?:[\.,]\s+|\s*)(?P<month_3>{lm}|{sm})(?:[\.,]\s+|\s*)(?P<year_3>{ly})',
    r'(?P<month_4>{lm}|{sm})\s+(?P<year_4>{ly})',
    r'(?P<month_5>{lnm}|{snm})/(?P<year_5>{ly})',
    r'(?P<year_6>{ly})',
    r'(?P<month_6>{sm})\s+(?P<day_4>(?={od})[0-9][0-9]?)..,\s*(?P<year_7>{ly})'
)

_pattern = '|'.join(
    i.format(
        sm=short_month_cap, lm=long_month_cap, snm=short_num_month_cap,
        lnm=long_num_month_cap, ld=long_day_cap, sd=short_day_cap,
        ly=long_year_cap, sy=short_year_cap, od=ordinal_day
    ) for i in formats
)

pattern = re.compile(_pattern)


def get_fields(match):
    if not match:
        return None
    return {
        k[:-2]: v
        for k, v in match.groupdict().items()
        if v is not None
    }

tests = r'''04/20/2009; 04/20/09; 4/20/09; 4/3/09
Mar-20-2009; Mar 20, 2009; March 20, 2009; Mar. 20, 2009; Mar 20 2009
20 Mar 2009; 20 March 2009; 20 Mar. 2009; 20 March, 2009
Mar 20th, 2009; Mar 21st, 2009; Mar 22nd, 2009
Feb 2009; Sep 2009; Oct 2010
6/2008; 12/2009
2009; 2010'''

for test_line in tests.split('\n'):
    for test in test_line.split('; '):
        print('{!r}: {!r}'.format(test, get_fields(pattern.fullmatch(test))))
    print('')

哪些输出:

'04/20/2009': {'month': '04', 'day': '20', 'year': '2009'}
'04/20/09': {'month': '04', 'day': '20', 'year': '09'}
'4/20/09': {'month': '4', 'day': '20', 'year': '09'}
'4/3/09': {'month': '4', 'day': '3', 'year': '09'}

'Mar-20-2009': {'month': 'Mar', 'day': '20', 'year': '2009'}
'Mar 20, 2009': {'month': 'Mar', 'day': '20', 'year': '2009'}
'March 20, 2009': {'month': 'March', 'day': '20', 'year': '2009'}
'Mar. 20, 2009': {'month': 'Mar', 'day': '20', 'year': '2009'}
'Mar 20 2009': {'month': 'Mar', 'day': '20', 'year': '2009'}

'20 Mar 2009': {'day': '20', 'month': 'Mar', 'year': '2009'}
'20 March 2009': {'day': '20', 'month': 'March', 'year': '2009'}
'20 Mar. 2009': {'day': '20', 'month': 'Mar', 'year': '2009'}
'20 March, 2009': {'day': '20', 'month': 'March', 'year': '2009'}

'Mar 20th, 2009': {'month': 'Mar', 'day': '20', 'year': '2009'}
'Mar 21st, 2009': {'month': 'Mar', 'day': '21', 'year': '2009'}
'Mar 22nd, 2009': {'month': 'Mar', 'day': '22', 'year': '2009'}

'Feb 2009': {'month': 'Feb', 'year': '2009'}
'Sep 2009': {'month': 'Sep', 'year': '2009'}
'Oct 2010': {'month': 'Oct', 'year': '2010'}

'6/2008': {'month': '6', 'year': '2008'}
'12/2009': {'month': '12', 'year': '2009'}

'2009': {'year': '2009'}
'2010': {'year': '2010'}

主要部分是formats变量，其中定义了所有不同的格式。它比定义的匹配略多，并且可以轻松扩展。

总体模式最终是:

'(?P<month_0>(?:0[1-9]|1[12])|(?:[1-9]|1[12]))/(?P<day_0>(?:0[1-9]|[12][0-9]|3[01])|(?:[1-9]|[12][0-9]|3[01]))/(?P<year_0>(?:[0-9][0-9])|(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3}))|(?P<month_1>(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\\-(?P<day_1>(?:0[1-9]|[12][0-9]|3[01])|(?:[1-9]|[12][0-9]|3[01]))\\-(?P<year_1>(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3}))|(?P<month_2>(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)|(?:January|February|March|April|May|June|July|August|September|October|November|December))(?:\\.\\s+|\\s*)(?P<day_2>(?:0[1-9]|[12][0-9]|3[01])|(?:[1-9]|[12][0-9]|3[01]))(?:,\\s+|\\s*)(?P<year_2>(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3}))|(?P<day_3>(?:0[1-9]|[12][0-9]|3[01])|(?:[1-9]|[12][0-9]|3[01]))(?:[\\.,]\\s+|\\s*)(?P<month_3>(?:January|February|March|April|May|June|July|August|September|October|November|December)|(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))(?:[\\.,]\\s+|\\s*)(?P<year_3>(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3}))|(?P<month_4>(?:January|February|March|April|May|June|July|August|September|October|November|December)|(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\\s+(?P<year_4>(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3}))|(?P<month_5>(?:0[1-9]|1[12])|(?:[1-9]|1[12]))/(?P<year_5>(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3}))|(?P<year_6>(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3}))|(?P<month_6>(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\\s+(?P<day_4>(?=(?:2?1st|2?2nd|2?3rd|[12]?[4-9]th|1[123]th|[123]0th|31st))[0-9][0-9]?)..,\\s*(?P<year_7>(?:[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]|[0-9][1-9][0-9]{2}|[1-9][0-9]{3}))'

这几乎不可能用手写。

可以在 _pattern 周围添加“随机文本之间”的边界。

我建议_pattern = r'\b(?:{})\b'.format(_pattern)。