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How to group and then 3D plot a column in a matrix?

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Suppletory on 20 Jul 2017
Edited: Carl on 24 Jul 2017
Dear All,
I have matrix M that is 2500x4 like so (I put in the headings myself):
Color X Y Z
42 1.006431 1.144329 92.1
43 1.006436 1.122343 61.1
42 1.006553 1.023647 54.1
33 1.006755 1.754235 73.2
47 1.006043 1.234565 87.6
39 1.006324 1.622433 99.5
... ... ... ...
I would like to plot the Color column as a 3D plot with X Y and Z as my coordinate system. Each point will vary according to the value of Color. However, since there are many variables, it may be smarter to put all the common X, Y, Z values into groups and averaging the Color in each group. X and Y can be 5 significant figures each and Z can be 2 significant figures. For example, at (1.0064,1.1443,92), the average color will be some value around 42. If you are confused please let me know. Thank you for your time.

Answers (1)

Carl on 24 Jul 2017
Edited: Carl on 24 Jul 2017
You can use the scatter3 function and specify the color for each one of your points. See the quick example below:
c = zeros(6,3);
data = [(1:6)', (1:6)', rand(6,1)];
% red if z greater than 0.5
c(data(:,3) > 0.5, 1) = 1;
% blue if z less than or equal to 0.5
c(data(:,3) <= 0.5, 3) = 1;
See the documentation for more details on using the scatter3 function:
Specifically, you can supply the value of c as a "three-column matrix of RGB triplets" as shown above, or define your own colormap and index into it.

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