Python 如果列表中的值以特定字符开头,请使用列表替换这些值
我有以下列表,我正在尝试将以Python 如果列表中的值以特定字符开头,请使用列表替换这些值,python,list,if-statement,list-comprehension,conditional-operator,Python,List,If Statement,List Comprehension,Conditional Operator,我有以下列表,我正在尝试将以23:开头的任何值替换为00:00:00.00 tc = ['00:00:00.360', '00:00:00.920', '00:00:00.060', '00:00:02.600', '23:59:55.680', '00:00:05.960', '00:00:01.040', '00:00:01.140', '00:00:01.060', '00:00:0
23:
开头的任何值替换为00:00:00.00
tc = ['00:00:00.360',
'00:00:00.920',
'00:00:00.060',
'00:00:02.600',
'23:59:55.680',
'00:00:05.960',
'00:00:01.040',
'00:00:01.140',
'00:00:01.060',
'00:00:01.480',
'00:00:00.140',
'00:00:00.280',
'23:59:59.800',
'00:00:01.200',
'00:00:00.400',
'23:59:59.940',
'00:00:01.220',
'00:00:00.380']
我能用正则表达式得到我需要的东西
tc = [re.sub(r'(\b23:)(.*)',r'00:00:00.00', item) for item in tc]
它给出了如下所示的预期结果
['00:00:00.360',
'00:00:00.920',
'00:00:00.060',
'00:00:02.600',
'00:00:00.00',
'00:00:05.960',
'00:00:01.040',
'00:00:01.140',
'00:00:01.060',
'00:00:01.480',
'00:00:00.140',
'00:00:00.280',
'00:00:00.00',
'00:00:01.200',
'00:00:00.400',
'00:00:00.00',
'00:00:01.220',
'00:00:00.380']
但是如果我使用下面的方法而不使用正则表达式,那么结果就不是我所期望的
tc = [item.replace(item, '00:00:00.00') for item in tc if item.startswith('23:')]
结果:
['00:00:00.00', '00:00:00.00', '00:00:00.00']
结果列表仅包含替换项,而不是整个列表。如何使用上述方法获取完整列表?您需要在三元运算符中包含else语句:
>>> [item.replace(item, '00:00:00.00') if item.startswith('23:') else item for item in tc]
['00:00:00.360',
'00:00:00.920',
'00:00:00.060',
'00:00:02.600',
'00:00:00.00',
'00:00:05.960',
'00:00:01.040',
'00:00:01.140',
'00:00:01.060',
'00:00:01.480',
'00:00:00.140',
'00:00:00.280',
'00:00:00.00',
'00:00:01.200',
'00:00:00.400',
'00:00:00.00',
'00:00:01.220',
'00:00:00.380']
甚至只是:
>>> ['00:00:00.00' if item.startswith('23:') else item for item in tc]
['00:00:00.360',
'00:00:00.920',
'00:00:00.060',
'00:00:02.600',
'00:00:00.00',
'00:00:05.960',
'00:00:01.040',
'00:00:01.140',
'00:00:01.060',
'00:00:01.480',
'00:00:00.140',
'00:00:00.280',
'00:00:00.00',
'00:00:01.200',
'00:00:00.400',
'00:00:00.00',
'00:00:01.220',
'00:00:00.380']
这与您的问题没有直接关系,但是执行
一些字符串.replace(一些字符串,不管什么)
没有多大意义,因为这会完全替换字符串。你也可以自己写任何东西。因此,对于您的最终代码示例,这将是tc=['00:00:00.00',对于tc-if-item.startswith('23:')中的item