CODEWITHSUNDEEP
matlab
gabboshow
gabboshow

Reputation: 5559

Define scatter3 colours in MATLAB

Is there a way to control the colours in scatter3?

In my clustering problem I have 2 vectors A = 80x3 containing my data and index containing the indices of the clusters. So for example the data point A(i,1) A(i,2) A(i,3) belongs to the cluster index(i).

With scatter3(A(:,1),A(:,2),A(:,3),50,index','filled') I plot all the data-points according to their clusters, but I would like to specify the colour for each group of points.

I tried with the Help, but I didn't manage.

Upvotes: 3

Views: 3389

Answers (1)

marsei
marsei

Reputation: 7751

You are nearly there. scatter3 provides several options to define the color scheme (see the doc here). One is indexing with scalars as you do right now. The coloring scheme is automatic in this case. Another option is to use triplets of values representing RGB colors.

For instance, for three colors you can define a custom colormap cmap.

color_1 = [1 0.2 0.4];
color_2 = [0.34 0.65 0.87];
color_3 = [0.5 0.5 0.5];

cmap = [color_1; color_2; color_3];

and then create an INDEX_color (Nx3) matrix based on your actual indexing

INDEX_color = cmap(INDEX,:);

For more groups, you can automatically create INDEX_color based on buil-in colormaps. cmap = colormap(jet(10)); will produce a 10x3 RGB matrix folowwing the jet colormap.

The following figure

enter image description here

is given by this code

A = [rand(20,3); rand(20,3)+1; rand(20,3)+2 ];
INDEX = [ones(20,1); ones(20,1)+1; ones(20,1)+2 ];

color_1 = [1 0.2 0.4];
color_2 = [0.34 0.65 0.87];
color_3 = [0.5 0.5 0.5];

cmap = [color_1; color_2; color_3];

INDEX_color = cmap(INDEX,:);

scatter3(A(:,1), A(:,2), A(:,3), 50, INDEX_color, 'filled')

Upvotes: 4

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