Convert template conditional into plugin code

[Mark.B]

Hi

I have the following template conditional, variants upon which I use quite a lot:

<if condition="!in_array($foruminfo['forumid'], array(1,2,3,4))">

I can work out how to format most conditionals if they are needed in php plugin code rather than in a template. However, I am unsure how to do this for the in_array stuff.

How would I format the above conditional to make it apply to a block of plugin code? (Assuming it's at a hook where $foruminfo is available).