MATLAB: How to make 2D plot of points with different colors?

Question

I want to make a 2D plot of points with different x, y coordinates and have colors depending on a separate variable. I have make column vectors for x and y coordinates and another column containing 1 or -1. I would like to represent the points with 1 as red and -1 as blue points. I have codes as follow:

x_dis=rho_rec(1:nDis,xCol,step);%x coordinates
y_dis=rho_rec(1:nDis,yCol,step); %y coordinates 
bv=rho_rec(1:nDis,bvCol,step); % 1 or -1

for i=1:1:nDis
    if bv(i)==1
        dis_color(i,1:3)=[0 0 1]; %blue
    elseif bv(i)==-1
        dis_color(i,1:3)=[1 0 0]; %red
    end
end

plot(x_dis,y_dis,'.','Color',dis_color(1:nDis,:))

However it doesn't work. How should I modify the code? Thank you.

Answer 1

I believe you mean to make a scatter plot. You need to use the scatter function. If that is the case, you do not pass on a 'Color' argument.

The following should work for you:

scatter(x_dis,y_dis,[],dis_color(1:nDis,:),'.')

The [] is a placeholder for marker size

Do you initialize dis_color elsewhere? You may wish to do that before your for loop.