Randomization... if not this then that

Here is my code:

random = rand(1)
if random <(1/4)
  tri1 = downtri 
   b1 = vertbaseq1
elseif random>=(1/4) && random<(2/4)
  tri1 = uptri 
  b1 = vertbaseq1
elseif random>=(2/4) && random<(3/4)
  tri1 = righttri 
  b1 = horzbaseq1
elseif random>=(3/4) && random<(4/4)
  tri1 = lefttri 
  b1 = horzbaseq1
end
if random <(1/4)
  tri2 = downtri 
  b2 = vertbaseq2
elseif random>=(1/4) && random<(2/4)
  tri2 = uptri 
  b2 = vertbaseq2
elseif random>=(2/4) && random<(3/4)
  tri2 = righttri 
  b2 = horzbaseq2
elseif random>=(3/4) && random<(4/4)
  tri2 = lefttri 
  b2 = horzbaseq2
end
...

So what this code basically does is randomize between four different triangles at four different locations. The problem: it randomizes the same triangle to each location. I need the some code that says something like if triangle 1 (tri1) is an up triangle (uptri) then triangle 2 will be any triangle that isn't an up triangle.

any help would be greatly, greatly! appreciated, Brett

Answer 1

[Image Analyst]

After your first if, have this instead of the second if:

if tri1 == uptri
  % Triangle 2 can't be an uptriangle.
  random = rand(1);
  if random <(1/3)
    tri2 = downtri 
    b2 = vertbaseq2
  elseif random>=(1/3) && random<(2/3)
    tri2 = righttri 
    b2 = horzbaseq2
  else
    tri2 = lefttri 
    b2 = horzbaseq2
  end
else
  % Triangle 2 can be anything.
  if random <(1/4)
    tri2 = downtri 
    b2 = vertbaseq2
  elseif random>=(1/4) && random<(2/4)
    tri2 = uptri 
    b2 = vertbaseq2
  elseif random>=(2/4) && random<(3/4)
    tri2 = righttri 
    b2 = horzbaseq2
  elseif random>=(3/4) && random<(4/4)
    tri2 = lefttri 
    b2 = horzbaseq2
  end
end

[Brett]

Sorry, I didn't explain the problem well - this does exactly what I said, so thank you. But what I need is that triangle 2 be any triangle that triangle 1 is not (if tri1 = uptri,then tri2 = [downtri, righttri or lefttri] or if tri1 = righttri, tri2 = [downtri, uptri or lefttri] etc). Is there a way to make it so tri2 doesn't equal the value of tri1?

[Image Analyst]

Try randperm then to make sure they are different:

random = randperm(4)
random1 = random(1)
random2 = random(2)
% random1 and random2 are guaranteed to be different
% First assign triangle1
if random1 == 1
  tri1 = downtri 
   b1 = vertbaseq1
elseif random1 == 2
  tri1 = uptri 
  b1 = vertbaseq1
elseif random1 == 3
  tri1 = righttri 
  b1 = horzbaseq1
else
  tri1 = lefttri 
  b1 = horzbaseq1
end

% Next assign triangle2
% Remember random1 and random2 are different
% so triangle2 will be different than triangle1.
if random2 == 1
   tri2 = downtri 
   b2 = vertbaseq2
elseif random2 == 2
  tri2 = uptri 
  b2 = vertbaseq2
elseif random2 == 3
  tri2 = righttri 
  b2 = horzbaseq2
else
  tri2 = lefttri 
  b2 = horzbaseq2
end

[Brett]

This works perfectly! I can't thank you enough!

[Image Analyst]

You're welcome. Not bad for me just writing it and not even being able to run it or test it!