Most vehicle license/number plate extractors I've found involve reading a plate from an image (OCR) but I'm interested in something that could tag instances of license plates in a body of text. Are there any such annotators out there?

  • 2
    $\begingroup$ Any particular country? Different countries have different license plate formats. Its a big world out there. $\endgroup$
    – Spacedman
    Commented Jul 24, 2014 at 11:48
  • $\begingroup$ @Spacedman Any country is fine :) $\endgroup$ Commented Jul 24, 2014 at 17:38

2 Answers 2


There are a lot of pretty decent tools out there for text annotation in general, and given the broad nature of the task you're approaching (license plates are about as general as words), the annotation tools you are looking at should probably come from the more classical tools for annotation.

There was actually a pretty good discussion about annotation tools on this question, which should actually apply to this problem. The most relied-upon thing in annotation right now is probably brat. You can learn more about brat here.

Hope that helps! Let me know if you've got any more questions.


This can be done using regular expressions.

2 letters followed by a number (\d denotes digits) would be

[A-Z]{2} \d*

2 or 3 letters followed by a number is

[A-Z]{2,3} \d*
  • $\begingroup$ I don't mean to be negative, but regular expressions are an extremely poor choice for this problem. Between state-by-state variation, vanity plates, and differing formats, regular expressions are a poor choice. $\endgroup$
    – indico
    Commented Jul 24, 2014 at 2:07
  • $\begingroup$ How many different variations are there? I'm from a different country. $\endgroup$
    – germcd
    Commented Jul 24, 2014 at 12:53
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    $\begingroup$ A conservative estimate would be 51, probably close to a few hundred. $\endgroup$
    – indico
    Commented Jul 24, 2014 at 16:18
  • $\begingroup$ Ah right I see the problem. I was thinking that I could find all the plates registered here with 3 regular expressions. $\endgroup$
    – germcd
    Commented Jul 24, 2014 at 16:55
  • $\begingroup$ @germcd Thanks for the attempt though! Glad to hear I wasn't the only person to think of regex too. $\endgroup$ Commented Jul 24, 2014 at 17:42

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