Fixing my counter statement.

So I have two arrays (x and y) that are 324 long columns. I need to separate the each pair(x,y) of points into what quadrant the point falls into when graphed. For example if the first x and y are (-3,4) I need to put that point into an array of the other points in the data that fall in quadrant two. What am I doing wrong?

Q=[x y];
for counter=1:length(Q) 
    if x(counter)>0 && y(counter)>0
        Q1=[x(x>0) y(y>0)'];
    end
    if x(counter)<0 && y(counter)>0
        Q2=[x(x<0) y(y>0)'];
    end
    if x(counter)<0 && y(counter1)<0
        Q3=[x(x<0) y(y<0)'];
    end
    if x(counter)>0 && y(counter1)<0
        Q4=[x(x>0) y(y<0)'];
    end
end

Answer 1

[the cyclist]

I would do it like this:

% Some pretend data
x = rand(324,1) - 0.5;
y = rand(324,1) - 0.5;

% First quadrant
Q1_index = (x>0) & (y>0);
Q1 = [x(Q1_index) y(Q1_index)]

% similar code for the other three quadrants ...

Answer 2

[John D'Errico]

Why all the tests?

whichQuadrant = @(x,y) 1 + floor(mod(atan2d(y,x)/90,4));