finding regular exprssions from a list of string examples

Question

Is it possible to find regular expressions given matching examples?

examples = [
     "my name is Alice",
     "my name is Alex",
     "my good name is Bruce"
]

I need to find a possible regular expression programmatically which matches all the above examples. For the given example set above, python regex would be my (.*)name is (.*) or my (\w)name is (\w).

EDIT: I need to write a script which automates the extraction of regex for me.

No, the question is how do i write a script which automatically extracts the regular expression when i present it with matching examples ?. You took a look at the examples and wrote a regex. I want a program to do that — Shivaprasad Bhat, Oct 23 '16 at 07:56
Do you need to find the regex programmatically, meaning you want a piece of software to give your the matching regex? If that is so, maybe do `(my name is Alice)|(my name is Alex)|(my good name is Bruce)`. That will be easy to string together with code. — Tammo Heeren, Oct 23 '16 at 07:57
`my name is John` is not in your examples. How should a piece of code know what portion of the sentence is the one that is allowed to vary? — Tammo Heeren, Oct 23 '16 at 08:00
It can know that, because it is presented with multiple examples. I can easily do this when the example set contains `my name is connor kelly`, `my name is alex`, `my name is bruce`. My script would generate regex `my name is (.*)` which would match `my name is john` as well. Since, in above example, `my good name is bruce` has an extra word `good` in between, i somehow need to render all the examples into having same length (length=no.of words here). — Shivaprasad Bhat, Oct 23 '16 at 08:05
@ShivaprasadBhat [Here](http://stackoverflow.com/a/3141762/1192111)'s a possible solution to your problem (it's in ruby, so you'll have to translate it to Python) — Francisco, Oct 23 '16 at 08:08
@hek2mgl It is not impossible. One answer is provided by Francisco Couzo — Shivaprasad Bhat, Oct 23 '16 at 08:20
Did you *read*, *understood* and implemented that? Meaning did you solved your problem or not? — hek2mgl, Oct 23 '16 at 12:54
Yes. I implemented it the same day i asked the question. I just uploaded the minimalistic version of the regex-utils i have been working on to github. https://github.com/shivylp/RegexUtils — Shivaprasad Bhat, Dec 04 '16 at 05:56
P.S. I did not refer the link posted by Francisco Couzo. So i don't know the approach used there. I found my own. — Shivaprasad Bhat, Dec 04 '16 at 06:13

score 0 · Answer 1 · answered Oct 23 '16 at 07:59

0

If it is just that, try:

regex = '(' + ')|('.join(examples) + ')'

answered Oct 23 '16 at 07:59

Tammo Heeren

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It's not that bad. It's doing what the OP requested. Generate a regex that matches all of his examples. – Tammo Heeren Oct 23 '16 at 08:10

score 0 · Accepted Answer · answered Dec 04 '16 at 06:15

0

I implemented a solution myself. I made a small python package out of it and put it in my Github repo @ http://github.com/shivylp/RegexUtils

If anyone is looking for something similar, can use it.

answered Dec 04 '16 at 06:15

Shivaprasad Bhat

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finding regular exprssions from a list of string examples

2 Answers2