Create custom matrix with user-defined parameters

Hi,

I would like help creating a custom matrix that follows this pattern:

[1 1 -1 1;
 1 1 1 -1;
 1 2 -1 1;
 1 2 1 -1;
 1 3 -1 1;
 1 3 1 -1;
 2 1 -1 1;
 2 1 1 -1;
 2 2 -1 1;
 2 2 1 -1;
 2 3 -1 1;
 2 3 1 -1;
 3 1 -1 1;
 3 1 1 -1;
 3 2 -1 1;
 3 2 1 -1;
 3 3 -1 1;
 3 3 1 -1;
 4 1 -1 1;
 4 1 1 -1;
 4 2 -1 1;
 4 2 1 -1;
 4 3 -1 1;
 4 3 1 -1]

I want the maximum number to which the first two columns count to be user-determined (e.g., x and y, respectively).

In the above example, x = 4 and y = 3.

Column one counts to x, repeating each integer (2y) times.

Column two counts to y, repeating each integer twice.

Columns three and four alternate between -1 and 1 for the entirety of the matrix.

So the total number of rows for the matrix is always (x * y * 2) which equals 24 in the above example.

Thanks in advance!

[madhan ravi]

more explanation needed

[Blake Seaton]

Sorry, I'm not sure what more I can provide. I would like a block of code that will take a number for x and a number for y and create a matrix with the posted pattern and explanation. There are roundabout ways of getting it done, but because I'm still somewhat of a novice, I can't seem to come up with an elegant way to do it.

Answer 1

[madhan ravi]

x = 4 ;
y = 3 ;
[ X, Y ] = meshgrid( 1 : x, 1 : y ) ;
Alternator = repmat( ( - 1 ) .^ ( 1 : numel( X ) ).', 1, 2) ;
z = [ X( : ), Y( : ) ] ;
Wanted = [ repelem( z, 2, 1 ), Alternator( : ) * [ 1, - 1 ] ]

[Blake Seaton]

Outstanding, thank you!

[Blake Seaton]

Follow up question:

How could this be modified so that the first two columns are never the same number? Following the same pattern as the original question, the end result would look like:

[1 2 -1 1;
 1 2 1 -1;
 1 3 -1 1;
 1 3 1 -1;
 2 1 -1 1;
 2 1 1 -1;
 2 3 -1 1;
 2 3 1 -1;
 3 1 -1 1;
 3 1 1 -1;
 3 2 -1 1;
 3 2 1 -1;
 4 1 -1 1;
 4 1 1 -1;
 4 2 -1 1;
 4 2 1 -1;
 4 3 -1 1;
 4 3 1 -1]

[madhan ravi]

 Wanted( Wanted(:, 1)  ~= Wanted(:, 2), :)

[Blake Seaton]

You are too good... thank you!