CODEWITHSUNDEEP
matlabloopsplotcolorslegend
Constantine Pat.
Constantine Pat.

Reputation: 59

Matlab legend for plotting in loop with different colors

I have a code in matlab in which i'm plotting several 2d points, which belong in 16 classes, so i use 16 different colors. Is there any easy way to have a legend that denote the class name for each color?

Code looks something like this:

for i=1:length(data) 
    color = class_color(i);
    plot(data(i,1),data(i,2),'*','Color',color);
    hold on;
end

Upvotes: 0

Views: 746

Answers (2)

Steve
Steve

Reputation: 1587

You could plot all the data points for a single class together with logical indexing.

Assuming you have the classes defined somewhere, say in class_number which is the same length as data, with entries ranging from 1 to 16, and c_colors, a cell array of length 16 with the colors corresponding to each class: then

for jj = 1:16
  mask = (class_number==jj);
  plot(data(mask,1),data(mask,2),'*','Color',c_colors{jj});
  hold on
end
hold off

(Not tested).

Then you can store the names of the classes in a cell array and call legend on that.

class_name{1} = 'Type a';
class_name{2} = 'Type b';
% etc, up to
class_name{15} = 'Type o';
class_name{16} = 'Type p';
legend(class_name);

Upvotes: 1

Arthur Tarasov
Arthur Tarasov

Reputation: 3791

That is a bad idea to use 16 colors to differentiate data points. Like colors will blend together. I suggest using different markers+colors. Four markers like '*' , 'x', '+', '.', etc. and four colors for each marker. Then you can use legend('Class 1','Class 2', Class n'). It should show each marker of the specific color. This will probably be the case when it is best to write out each line without loop and add %comments after each marker/color/class describing what it is, in case you have to come back to this code later. It is not really a solution you are asking for, but this is how I would do it.

Upvotes: 0

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