Scatter with different colors based on id column

I am trying to scatter a bunch of data stored in a matrix that I want to color code based on an ID. The matrix rows are of the following form:

[positionX, positionY, ID].

The matrix's rows can vary in number and there can be different amount of unique IDs. IDs are always integers in increasing order. Therefore I prefer not to split the matrix into smaller matrices based on ID.

Are there any good solutions to how this can be done? Can a condition be given to the scatter function? (I can't find this in any documentation).

Answer 1

[Ive J]

What abou this?

scatter(positionX, positionY, sz, ID, 'filled')

% example
scatter(rand(10, 1), rand(10, 1), 200, randi(5, 10, 1),...
    'filled',...
    'MarkerFaceAlpha', 0.7,...
    'MarkerEdgeColor', 'k')
grid on

[Rasmus Hogslätt]

What do you mean that the argument ID does in the scatter you mentioned? I want points with the same ID to have the same color. I am not sure what your randi(5, 10, 1) does.

[Ive J]

If you'd tried the snippet I just wrote above, you would realize each value in ID corresponds to a distinct color code on the scatter plot. For more info see 4th argument of scatter.

Below (also above example) is just an example showing the structure of your data (ID is integer).

% sample data
positionX = rand(10, 1);
positionY = rand(10, 1);
ID = randi(5, 10, 1);
sz = 200; % marker size

scatter(positionX, positionY, sz, ID,...
    'filled',...
    'MarkerFaceAlpha', 0.7,...
    'MarkerEdgeColor', 'k')
grid on
text(positionX, positionY, string(ID), 'HorizontalAlignment', 'center') % show IDs on each marker

[Rasmus Hogslätt]

Thank you! This made me understand.