python之使用正则表达式删除字符串末尾不可预测的日期格式

我通过以下方式获取字符串，最后以随机模式显示日期。但它只会包含下划线、斜杠、数字或连字符。

TRAVEL_DELAY_01072015 
TRAVEL_DELAY_01_07_2015 
TRAVEL_DELAY_2015/01/04 
TRAVEL_DELAY_2015-01-04 

我只需要从上面的字符串中取出 TRAVEL_DELAY。我正在为此使用正则表达式，但不起作用:

m = re.match("^(.*)[_0-9\/.]+", abovestring) 

请您参考如下方法:

如果您只想拆分日期:

s="""TRAVEL_DELAY_01072015 
TRAVEL_DELAY_01_07_2015 
TRAVEL_DELAY_2015/01/04 
TRAVEL_DELAY_2015-01-04""" 
 
for line in s.splitlines(): 
    date = line.split("_",2)[-1] 
 
01072015 
01_07_2015 
2015/01/04 
2015-01-04 

或者str.replace，不需要正则表达式:

for line in s.splitlines(): 
    date = line.replace("TRAVEL_DELAY_","") 
    print(date) 
 
 01072015 
 01_07_2015 
 2015/01/04 
 2015-01-04 

如果您实际上是在尝试解析日期，您可以使用 dateutil 并修复字符串:

from dateutil import parser 
for line in s.splitlines(): 
    date = line.replace("TRAVEL_DELAY_","") 
    if any(ch in date for ch in ("/","-","_")): 
        print(parser.parse(date.replace("_","-"))) 
    else: 
        date = "{}-{}-{}".format(date[:2],date[2:4],date[4:]) 
        print(parser.parse(date)) 
 
 
2015-01-07 00:00:00 
2015-01-07 00:00:00 
2015-01-04 00:00:00 
2015-01-04 00:00:00 

如果数字只在日期中，而您实际上想要的是字符串而不是日期:

 s="""TRAVEL_DELAY_01072015 
TRAVEL_DELAY_01_07_2015 
TRAVEL_DELAY_2015/01/04 
Travel_Delay_Data_2015/01/04 
TRAVEL_DELAY_2015-01-04""" 
 
for line in s.splitlines(): 
    ind = next(ind for ind, ele in enumerate(line) if ele.isdigit()) 
    s = line[:ind-1] 
    print(s) 
 
TRAVEL_DELAY 
TRAVEL_DELAY 
TRAVEL_DELAY 
Travel_Delay_Data 
TRAVEL_DELAY