CODEWITHSUNDEEP
pythonregexpython-3.x
ds_user
ds_user

Reputation: 2179

Extracting multiple date formats through regex in python

I am trying to extract date from text in python. These are the possible texts and date patterns in it.

"Auction details: 14 December 2016, Pukekohe Park"
"Auction details: 17 Feb 2017, Gold Sacs Road"
"Auction details: Wednesday 27 Apr 1:00 p.m. (On site)(2016)"
"Auction details: Wednesday 27 Apr 1:00 p.m. (In Rooms - 923 Whangaa Rd, Man)(2016)"
"Auction details: Wed 27 Apr 2:00 p.m., 48 Viaduct Harbour Ave, Auckland, (2016)"
"Auction details: November 16 Wednesday 2:00pm at 48 Viaduct Harbour Ave, Auckland(2016)"
"Auction details: Thursday, 28th February '19"
"Auction details: Friday, 1st February '19"

This is what I have written so far,

mon = ' (?:Jan(?:uary)?|Feb(?:ruary)?|Mar(?:ch)?|Apr(?:il)?|May|Jun(?:e)?|Jul(?:y)?|Aug(?:ust)?|Sep(?:tember)?|Oct(?:ober)?|(Nov|Dec)(?:ember)?) '
day1 = r'\d{1,2}'
day_test = r'\d{1,2}(?:th)|\d{1,2}(?:st)' 
year1 = r'\d{4}'
year2 = r'\(\d{4}\)'
dummy = r'.*'

This captures cases 1,2.

match = re.search(day1 + mon + year1, "Auction details: 14 December 2016, Pukekohe Park")
print match.group()

This somewhat captures case 3,4,5. But it prints everything from the text, so in the below case, I want 25 Nov 2016, but the below regex pattern gives me 25 Nov 3:00 p.m. (On Site)(2016).

So Question 1 : How to get only the date here?

match = re.search(day1 + mon + dummy + year2, "Friday 25 Nov 3:00 p.m. (On Site)(2016)")
print match.group()

Question 2 : Similarly, how do capture case 6,7 and 8 ?? What is the regex should be for that?

If not, is there any other better way to capture date from these formats?

Upvotes: 3

Views: 438

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626936

You may try 

((?:(?:Jan(?:uary)?|Feb(?:ruary)?|Mar(?:ch)?|Apr(?:il)?|May|Jun(?:e)?|Jul(?:y)?|Aug(?:ust)?|Sep(?:tember)?|Oct(?:ober)?|(?:Nov|Dec)(?:ember)?)\s+\d{1,2}(?:st|nd|rd|th)?|\d{1,2}(?:st|nd|rd|th)?\s+(?:Jan(?:uary)?|Feb(?:ruary)?|Mar(?:ch)?|Apr(?:il)?|May|Jun(?:e)?|Jul(?:y)?|Aug(?:ust)?|Sep(?:tember)?|Oct(?:ober)?|(?:Nov|Dec)(?:ember)?)))(?:.*(\b\d{2}(?:\d{2})?\b))?

See the regex demo.

Note I made all groups in the regex blocks non-capturing ((Nov|Dec) -> (?:Nov|Dec)), added (?:st|nd|rd|th)? optional group after day digit pattern, changed the year matching pattern to \b\d{2}(?:\d{2})?\b so that it only match 4- or 2-digit chunks as whole words, and created an alternation group to account for dates where day comes before month and vice versa.

The day and month are captured into Group 1 and the year is captured into Group 2, so the result is the concatenation of both.

NOTE: In case you need to match years in a safer way you may want to precise the year pattern. E.g., if you want to avoid matching the 4- or 2-digit whole words after :, add a negative lookbehind:

year1 = r'\b(?<!:)\d{2}(?:\d{2})?\b'
            ^^^^^^

Also, you may add word boundaries around the whole pattern to ensure a whole word match.

Here is the Python demo:

import re
mon = r'(?:Jan(?:uary)?|Feb(?:ruary)?|Mar(?:ch)?|Apr(?:il)?|May|Jun(?:e)?|Jul(?:y)?|Aug(?:ust)?|Sep(?:tember)?|Oct(?:ober)?|(?:Nov|Dec)(?:ember)?)'
day1 = r'\d{1,2}(?:st|nd|rd|th)?'
year1 = r'\b\d{2}(?:\d{2})?\b'
dummy = r'.*'

rx = r"((?:{smon}\s+{sday1}|{sday1}\s+{smon}))(?:{sdummy}({syear1}))?".format(smon=mon, sday1=day1, sdummy=dummy, syear1=year1)
# Or, try this if a partial number before a date is parsed as day:
# rx = r"\b((?:{smon}\s+{sday1}|{sday1}\s+{smon}))(?:{sdummy}({syear1}))?".format(smon=mon, sday1=day1, sdummy=dummy, syear1=year1)
strs = ["Auction details: 14 December 2016, Pukekohe Park","Auction details: 17 Feb 2017, Gold Sacs Road","Auction details: Wednesday 27 Apr 1:00 p.m. (On site)(2016)","Auction details: Wednesday 27 Apr 1:00 p.m. (In Rooms - 923 Whangaa Rd, Man)(2016)","Auction details: Wed 27 Apr 2:00 p.m., 48 Viaduct Harbour Ave, Auckland, (2016)","Auction details: November 16 Wednesday 2:00pm at 48 Viaduct Harbour Ave, Auckland(2016)","Auction details: Thursday, 28th February '19","Auction details: Friday, 1st February '19","Friday 25 Nov 3:00 p.m. (On Site)(2016)"]  
for s in strs:
    print(s)
    m = re.search(rx, s)
    if m:
        print("{} {}".format(m.group(1), m.group(2)))
    else:
        print("NO MATCH")

Output:

Auction details: 14 December 2016, Pukekohe Park
14 December 2016
Auction details: 17 Feb 2017, Gold Sacs Road
17 Feb 2017
Auction details: Wednesday 27 Apr 1:00 p.m. (On site)(2016)
27 Apr 2016
Auction details: Wednesday 27 Apr 1:00 p.m. (In Rooms - 923 Whangaa Rd, Man)(2016)
27 Apr 2016
Auction details: Wed 27 Apr 2:00 p.m., 48 Viaduct Harbour Ave, Auckland, (2016)
27 Apr 2016
Auction details: November 16 Wednesday 2:00pm at 48 Viaduct Harbour Ave, Auckland(2016)
November 16 2016
Auction details: Thursday, 28th February '19
28th February 19
Auction details: Friday, 1st February '19
1st February 19
Friday 25 Nov 3:00 p.m. (On Site)(2016)
25 Nov 2016

Upvotes: 3

Related Questions