Python regex on numbers

Question

Is it possible to use regex on a number instead of a string?

For example: I have a field in a mongodb that contains the numeric value 1234567 (not stored as a string for sorting purposes etc.). Now I want to use regex to find parts of this number, i.e. 456.

On a database-field that contains a string "1234567" this is easy: I just pass re.compile("456") to my database query. However re.compile(456) gets me the following:

TypeError: first argument must be string or compiled pattern

Any hints on how to accomplish this? Storing my numbers as strings is not really an option, since I would lose lots of other possibilities (like gt/lt, sorting etc.).

Update: Also, I'm passing the regex right into the db-query to filter results, so I cannot pull up an individual field, convert it's content to a string and then use the regex on it.

Convert that field to string first using `str` and then apply regex on it. — Ashwini Chaudhary, Sep 01 '13 at 10:15

score 2 · Answer 1 · answered Sep 01 '13 at 10:14

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You can convert a number to a string using the built-in str function:

str(456)

answered Sep 01 '13 at 10:14

RichieHindle

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I wish it was that easy ;-) I can't match against a number: TypeError: expected string or buffer. And converting my numeric fields in mongodb is not an option either as mentioned above. – user915245 Sep 01 '13 at 12:53

score 1 · Answer 2 · edited May 23 '17 at 10:31

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Marking as duplicate: MongoDB Regex Search on Integer Value

db.test.find({ $where: "/^123.*/.test(this.example)" })
{ "_id" : ObjectId("4bfc3187fec861325f34b132"), "example" : 1234 }

edited May 23 '17 at 10:31

Community

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answered Sep 01 '13 at 13:02

planestepper

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I'm reluctant to use javascript in my query for performance-reasons. Mongodb allows regex-filtering with the $regex-operator ...any insights on how to use this instead? – user915245 Sep 01 '13 at 13:54
Tried that, doesn't work – planestepper Sep 01 '13 at 15:10
You should benchmark and compare against your constraints. See http://docs.mongodb.org/manual/core/server-side-javascript/ – planestepper Sep 01 '13 at 15:12

score 0 · Answer 3 · answered Sep 01 '13 at 20:40

This isn't possible with MongoDB. Depending on your application, you might be able to store these numbers as string-typed values instead of numbers. In Python:

db.collection.insert({"my_number": "12345678"})

For phone numbers or zipcodes where arithmetic operations like $inc don't make sense, but where you want to use a regex to search your data, this could make sense.

An alternate approach could be to store each number both as a string and as a number:

db.collection.insert({"s": "12345678", "n": 12345678})

Python regex on numbers

3 Answers3