Using a for loop to graph values using different colors

I'm using some distances and I want to plot them. On my plot they should have a different color depending on how far away the are. Right now when I run my code, they're all being displayed with the same color. How can I make my distances different colors depending on their distance?

clear all
close all

data = [3 24 30 26 22 14 15 7 5 9];
t = (1:length(data));


for i = 1:length(data);
 
  if data(data <= 30 & data > 20)
    scatter(t,data,'.g');
    hold on;
  elseif data(data <= 20 & data > 10)
      scatter(t,data,'.y');
      hold on;
  elseif data(data <= 10 & data >= 0)
      scatter(t,data,'.r');
      hold on;
          
  end
xlabel('time (seconds)')
xlim([0 13])
ylabel('distance(meters)')
ylim([0 35])
title('Distance of Vehicle Over Time')
end

Answer 1

[Ameer Hamza]

There were issues with the if conditions. Check the corrected code. Also, note that you were plotting to scatter plot with all points.

clear all
close all

data = [3 24 30 26 22 14 15 7 5 9];
t = (1:length(data));


for i = 1:length(data)
    
    if data(data(i) <= 30 & data(i) > 20)
        scatter(t(i),data(i),'+b', 'Linewidth', 2);
        hold on;
    elseif data(data(i) <= 20 & data(i) > 10)
        scatter(t(i),data(i),'+m', 'Linewidth', 2);
        hold on;
    elseif data(data(i) <= 10 & data(i) >= 0)
        scatter(t(i),data(i),'+r', 'Linewidth', 2);
        hold on;
        
    end
    xlabel('time (seconds)')
    xlim([0 13])
    ylabel('distance(meters)')
    ylim([0 35])
    title('Distance of Vehicle Over Time')
end

Answer 2

[Turlough Hughes]

If you want to use scatter so that the color depends on distance, this is how you do it:

% Data
clear all
close all
data = [3 24 30 26 22 14 15 7 5 9];
t = (1:length(data));

scatter(t,data,[],data,'filled') %      < modified code

xlabel('time (seconds)')
xlim([0 13])
ylabel('distance(meters)')
ylim([0 35])
title('Distance of Vehicle Over Time')

If you specifically require 3 colors, you have the option of setting the colormap with just three sets of color triplets as follows:

colormap([1 0 0; 0 1 0; 0 0 1])

See documentation for scatter and colormap.

[Stephen23]

+1 good use of MATLAB