implementing set theory operations in php

Question

How to implement set theory operations in pure php?

score 10 · Accepted Answer · answered Aug 17 '10 at 02:26

10

Which operations are you looking for? What are you trying to accomplish?

In PHP an array is (imperfectly) analogous to a set, and PHP has array_intersect, array_merge (union), and array_diff (complement) functions built in. There's also array_uintersect and array_udiff for handling complex objects whose comparisons are not so straightforward.

Is there further functionality you need?

answered Aug 17 '10 at 02:26

Jordan Running

3

It's worth noting that array_merge isn't a true union according to set theory. You have to do array_merge then array_unique on the result otherwise you can end up with duplicates. The link that Strae provided in his answer to [Programming PHP](http://oreilly.com/catalog/progphp/chapter/ch05.html) demonstrates this. – David Kanenwisher Jun 05 '14 at 20:35

score 2 · Answer 2 · answered Aug 17 '10 at 02:27

2

Probably you'll already saw those links:

answered Aug 17 '10 at 02:27

Strae

For comparing non-scalar values, such as stdClass objects and other data types. – Justin Mitchell Jan 28 '16 at 00:57
https://web.archive.org/web/20201021103045/http://jamietalbot.com/2010/02/04/set-operations-in-php/ – Serhii Smirnov Nov 21 '22 at 12:48
https://web.archive.org/web/20080905054045/http://oreilly.com/catalog/progphp/chapter/ch05.html – Serhii Smirnov Nov 21 '22 at 12:49

2 Answers2