OK, say I wanted to take a matrix
[1,2,3]
[4,7,3]
[9,5,6]
and take off the first row so it was
[2,3]
[7,3]
[5,6]
how could i do this?  The only way I've been able to do this would be using Matrix to list, but that takes a lot of space and is slow, so...

Hmmm, I'm tempted to do some sort of fancy list manipulations and such, but I have another idea that may or may not work.

I assume these values will be accessed at some time in the program, so what I'm thinking is instead of changing the matrix, you could have a 'shift' variable that you can change.  Instead of saying [A](A,B) you would have [A](A+S,B) where S is the shift variable.  To simulate shifting the matrix over by one, you could instead just increase S by 1.

Alrighty then, what you need is a radial List!

Basicaly instead of moving the Matrix around so that the begining is at colomn 1, you move a pointer around that says where column 1 is.  Does that make sense?  I can run up some code if you like.

Sure.  I used this technique on a snake game i made.  It s prime example of how you want to move a whole bunch of elements down a list without losing much speed.

So here we have a list of 10 numbers (I'll use lists, but it still applies to matrixes)

{1,2,3,4,5,6,7,8,9,0->L1
20->S                                //We set the shift to 20.  If it goes negative, bad things happen :P
"1+10fPart((X+S)/10->Y1         //This is our magic formula, using modulus arithmetic, it gives us
                               //the element we want but accounts for the shift
                               //It is stored to Y1 for easy use :P
While 1

For(F,1,10                 //Just some simple code to display the list from 'start' to 'finish'
Output(1,F,L1(Y1(F           //But using the formula, so in perspective of the shift
End

Repeat Ans
getKey -> K
End

S + (K=24) - (k=26)    //You can change the shift with your arrow keys

End


Well let's look at it his way.  What this allows you to do is "rotate" the elements of a list through that list, and you can read and write to it normaly.  To do as you wanted, when you shifted the elements down, one would get pushed off the edge and go around to slot 10.  You can then overwrite it with your random value, and we have a scrolling list!

With lists, to get out the first element we use cumSum and /delta/List combo.

Can a similar thing be done in Matrices? I have to get the calc to test. I am pretty sure cumSum works with matrices but /delta/List don't.

Oh, ok, i see what you're saying. This would be amazing and exactly what i need... except that i cant have it wrap

Hmmm, I'm not quite sure what you mean.  Here, take a look at this slightly modified code

{1,2,3,4,5,6,7,8,9,0->L1
0->S                               
"1+10fPart((X+S)/10->Y1          //yay magic formula
                             
While 1

For(F,1,10                  //Display the entire linked list so you can see whats going on
Output(1,F,L1(Y1(F           //Displays elements from 1 to 10
End
rand(20

S+1->S                        //Increase shift
randInt(0,9->L1(Y1(10        //Add random number onto the 'end' of the list, which is element 10

End
I believe that does exactly what you are looking for.  Do you see how it works?  The numbers do wrap every time i change the shift, but then i overwrite them with the new random number that is being added onto the end of the list (End of the list is element 10)

Yes I see it, but I have to have
[1,2,3]
[2,3,4]
not say,
[2,3,1]
[3,4,2]
Here's an explanation: XLib Tilemap