Picking a random member of a Type List

BlitzMax Forums/BlitzMax Beginners Area/Picking a random member of a Type List

Ryan Burnside

(Posted 2006) [#1]

Let me introduce a problem,

I have a tlist that contains all my boss_fragment instances. The name of the tlist is called boss_fragment_list. I need to pick any instance from that list at random and tell it to proform a spawn() function how would this be done?

Thanks in advance.

Grey Alien

(Posted 2006) [#2]

you know how big the list is (List.Count) so you can make a random number from 1 to Count. Then loop through the list with For m:MyType = Each In MyList and keep a counter incrementing each time and when the counter is the same as the precalculated random number, use Exit to break out of the list and m is set to the random type.

Hope that makes sense.

Ryan Burnside

(Posted 2006) [#3]

Ok thanks, sometimes I tend to overcomplicatte things.

Perturbatio

(Posted 2006) [#4]

keep a counter incrementing each time and when the counter is the same as the precalculated random number, use Exit to break out of the list and m is set to the random type.

Or just use ValueAtIndex.

Eric	(Posted 2006) [#5]

Agree with Perturbatio

Local P1:TParticle=TParticle(ParticleList.ValueAtIndex(A))

Chris C

(Posted 2006) [#6]

ValueatIndex uses a loop too, so bare in mind it will be as slow as the first method

be nice if you could go straight to index A ....

Perturbatio

(Posted 2006) [#7]

be nice if you could go straight to index A ....

you could always use an array like this

Ryan Burnside

(Posted 2006) [#8]

Well I will be having hundreds of objects checking each other at once so optomizations are very important.

N	(Posted 2006) [#9]

Ryan: Use my IList code if you'll be having hundreds of objects. It's much faster if you're sorting or getting an object at a specific index.

Using my code you can do pretty much the same thing as with TLists for getting objects at a specific index:

Local f:Foo = Foo(MyList.ValueAtIndex( Rand( 0, MyList.Count( )-1 ) ))

mindstorms

(Posted 2006) [#10]

That looks good, Noel...What type should I use for what sort of problems?

N	(Posted 2006) [#11]

I use hash tables for storing data over long periods of time (it pretty much ensures that the data is going to stay in memory since it's going to have a reference until I remove it from the table). Binary trees.. Um, yeah, not sure what you'd use those for, I just wrote it for fun. And you can probably find some use for a linked list where others fail.

mindstorms

(Posted 2006) [#12]

Thanks, Noel

Ryan Burnside

(Posted 2006) [#13]

Yes, thanks Noel, do you wish to be credited in my game?
P.S. Lego for the win!!

N	(Posted 2006) [#14]

No, don't care.

Ryan Burnside

(Posted 2006) [#15]

Actually speed isn't important in this case here is my function.

It says Compile Error: Unable to convert from 'boss_fragment' to 'Int'

Function choose_cell()
	Local member%=Rand(1,CountList(boss_fragment.boss_fragment_list))
	Local counter%=0
	For Local i:boss_fragment=EachIn(boss_fragment.boss_fragment_list)
	 counter:+1
		If counter=member
			Return i
			Exit
		End If
	Next
End Function

N	(Posted 2006) [#16]

Function choose_cell:boss_fragment()