Extracting dates using regex following several formats

Question

(?:\d{1,2}[\-\/])?(?: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]*(?:\d{1,2}[\-\/\.)\s,]*)+(?:\d{2,4})(?: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]*(?:\d{1,2}[\-\/\.),]*)

I was trying to extract dates from the text from these ff. format:

January 1, 2020
January 01, 2020
JANUARY 1, 2020
JANUARY 01, 2020
Jan. 1, 2020
Jan. 01, 2020
JAN. 1, 2020
JAN. 01, 2020
2020 January 1
2020 January 01
2020 Jan. 1
2020 Jan. 01
2020 JAN. 1
2020 JAN. 01
01/01/2020
2020/01/01
01.01.2020
2020.01.01
01-01-2020
2020-01-01

Here's a sample. The problem is when it tries to extract from this format 2020 JAN. 1 , 2020 JAN. 01, 2020 Jan. 01, 2020-01-01.

I wouldn't do this with one regex, but with one regex per sample/ format. — Christian Baumann
– Christian Baumann, Commented Oct 5, 2020 at 11:36
The texts are from document, it is extracted using tesseract. Date formats can be any of the following mentioned above. How would I do it your way? Thanks — Matt Mateo
– Matt Mateo, Commented Oct 5, 2020 at 11:44

Wiktor Stribiżew · Accepted Answer · 2020-10-05 12:42:13Z

1

You can use

pattern = r"""(?ix)
  \b(?:Jan(?:uary)?|Feb(?:ruary)?|Mar(?:ch)?|Apr(?:il)?|May|June?|July?|Aug(?:ust)?|Sep(?:tember)?|Oct(?:ober)?|(?:Nov|Dec)(?:ember)?) [\s.]* (?:0?[1-9]|[12][0-9]|3[01]) [\s,.]* (?:19|20)(?:\d{2})? # Jan 01 2000
|
  (?<!\d)(?:19|20)(?:\d{2})? [\s,.]* (?:Jan(?:uary)?|Feb(?:ruary)?|Mar(?:ch)?|Apr(?:il)?|May|June?|July?|Aug(?:ust)?|Sep(?:tember)?|Oct(?:ober)?|(?:Nov|Dec)(?:ember)?) [\s.]* (?:0?[1-9]|[12][0-9]|3[01]) # 2000 Jan 01
|
 (?<!\d)
   (?:
    (?:0?[1-9]|1[012])[-/.]?(?:0?[1-9]|[12][0-9]|3[01])[-/.]?(?:19|20)\d\d # MM/dd/yyyy
     |
    (?:19|20)\d\d[-/.]?(?:0?[1-9]|1[012])[-/.]?(?:0?[1-9]|[12][0-9]|3[01]) # yyyy/MM/dd
   )
 (?!\d)"""

See the regex demo

The i modifier flag enables case insensitive matching and x enables the VERBOSE mode.

edited Oct 5, 2020 at 12:42

answered Oct 5, 2020 at 12:26

Wiktor Stribiżew

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2 Comments

Matt Mateo Over a year ago

It matches FEB-200 and 02 February 2

Wiktor Stribiżew Over a year ago

@MattMateo Better now? Please adjust the pattern as you see fit, we do not see all your data.

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