Link specific coordinates to a color when plotting them

Hello I am wondering if there is a way to link specific coordinates in a matrix to always be plotted in a specific color. like if I had the set of coordinates shown below and i want the first 4 sets to always be plotted in red and the next 3 always plotted in green whenever they are being plotted so that even if I clear the axes and replot those coordinates will always appear in the color they were set to.

A = [38.8197976955836	-29.0434116907097
    -37.0532684880158	0.644925865563445
    -4.49735986053992	57.3402937422674
    -43.7442096431328	38.5935144262550
    41.5359946082739	41.4696332098067
    57.3572679057450	8.87552592324304
    -29.8320366435934	-43.1286701525403];

Answer 1

[David Hill]

red=[1 0 0];
green = [0 1 0];
color=[red;red;red;red;green;green;green];%make color array for the colors you want at each index
scatter(A(:,1),A(:,2),[],color);%not sure what kind of plot you want

As long as the index does not change for the colors you want, then the above example should work.

[David Hill]

You could also use a colormap to map what you want for your plotting colors.

Answer 2

[Adam Danz]

When you use plot(x,y) it returns 1 handles and you cannot specify different colors to objects within the same handle.

You can use gscatter() (stats toolbox) to create grouped scatter points where you can specify the color (and size of markers) of each group.

h = gscatter(A(:,1),A(:,2),[1 1 1 1 2 2 2],[1 0 0; 0 1 0])
%                          _______________ here we define the groups by row
%                                          ______________ here we define the colors for each group

If you don't have stats toolbox, you can separate the rows of A and plot them as individual objects.

h1 = plot(A(1:4,1),A(1:4,2), 'ro');
hold on
h2 = plot(A(5:end,1),A(5:end,2), 'go');

[Vance Blake]

So with using the g scatter tool would it make more sense to replace any piece of code that use the plot command with g scatter or just clear the axes and use g scatter to replot all the points with their specified color when I need to ??

[Adam Danz]

If you're just plotting scatter points, then yes, you can replace plot() with scatter() but you also need to check that the other inputs OK.

David Hill's answer might suit your needs better since it does not spit the data into different graphics handles.

[Vance Blake]

@adam yeah im reading up on them both right now because i do like how the points are stored in separate groups but that might make removing them harder than necessary based on how this thread is going lol.

[Adam Danz]

Yeah, both gscatter() and scatter() have pros and cons that vary based on the context of the problem. Based on your context (from another post), I think scatter() will keep your data more organized.