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Python regex match date

What regular expression in Python do i use to match dates like this: "11/12/98"?

4 Answers
4

Instead of using regex, it is generally better to parse the string as a datetime.datetime object:

datetime.datetime

In [140]: datetime.datetime.strptime("11/12/98","%m/%d/%y")
Out[140]: datetime.datetime(1998, 11, 12, 0, 0)

In [141]: datetime.datetime.strptime("11/12/98","%d/%m/%y")
Out[141]: datetime.datetime(1998, 12, 11, 0, 0)


You could then access the day, month, and year (and hour, minutes, and seconds) as attributes of the datetime.datetime object:

datetime.datetime

In [143]: date.year
Out[143]: 1998

In [144]: date.month
Out[144]: 11

In [145]: date.day
Out[145]: 12


To test if a sequence of digits separated by forward-slashes represents a valid date, you could use a try..except block. Invalid dates will raise a ValueError:

try..except

ValueError

In [159]: try:
.....: datetime.datetime.strptime("99/99/99","%m/%d/%y")
.....: except ValueError as err:
.....: print(err)
.....:
.....:
time data '99/99/99' does not match format '%m/%d/%y'


If you need to search a longer string for a date,
you could use regex to search for digits separated by forward-slashes:

In [146]: import re
In [152]: match = re.search(r'(d+/d+/d+)','The date is 11/12/98')

In [153]: match.group(1)
Out[153]: '11/12/98'


Of course, invalid dates will also match:

In [154]: match = re.search(r'(d+/d+/d+)','The date is 99/99/99')

In [155]: match.group(1)
Out[155]: '99/99/99'


To check that match.group(1) returns a valid date string, you could then parsing it using datetime.datetime.strptime as shown above.

match.group(1)

datetime.datetime.strptime

I find the below RE working fine for Date in the following format;

It can accept year from 2000-2099

Please do not forget to add $ at the end,if not it accept 14-11-201 or 20177

date="13-11-2017"

x=re.search("^([1-9] |1[0-9]| 2[0-9]|3[0-1])(.|-)([1-9] |1[0-2])(.|-|)20[0-9][0-9]$",date)

x.group()


output = '13-11-2017'

Using this regular expression you can validate different kinds of Date/Time samples, just a little change is needed.

^dddd/(0?[1-9]|1[0-2])/(0?[1-9]|[12][0-9]|3[01]) (00|[0-9]|1[0-9]|2[0-3]):([0-9]|[0-5][0-9]):([0-9]|[0-5][0-9])$ -->validate this: 2018/7/12 13:00:00

^dddd/(0?[1-9]|1[0-2])/(0?[1-9]|[12][0-9]|3[01]) (00|[0-9]|1[0-9]|2[0-3]):([0-9]|[0-5][0-9]):([0-9]|[0-5][0-9])$

for your format you cad change it to:

^(0?[1-9]|[12][0-9]|3[01])/(0?[1-9]|1[0-2])/dd$ --> validates this: 11/12/98

^(0?[1-9]|[12][0-9]|3[01])/(0?[1-9]|1[0-2])/dd$

Well, from my understanding, simply for matching this format in a given string, I prefer this regular expression:

pattern='[0-9|/]+'

to match the format in a more strict way, the following works:

pattern='(?:[0-9]2/)2[0-9]2'

Personally, I cannot agree with unutbu's answer since sometimes we use regular expression for "finding" and "extract", not only "validating".

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