How to Plot data groups with different colors?

I have latitude, longitude and depth data. which I plotted them as below;

These depth data range between 0 -1000km.

I want each 'circle' (data point) to have different Markerface colours based on the depth group; such as 0-100 --> yellow; 101-300 --> blue; 301-1000 --> red. Could someone please help me with how to do this?

Data=load('Depth.txt','-ascii'); 

lon=Data(:,1); lon=360+lon;
lat=Data(:,2);
depth=Data(:,3);n=length(depth);

figure(1);clf;axis equal;hold on;

plot(lon,lat,'o');

ylabel('latitude (deg)');xlabel('longitude (deg)')
grid minor; 
title('Depth distribution')

Answer 1

[Voss]

One way is to plot one line per depth interval, each with a different Color/MarkerFaceColor:

% first, I make up some random data since I don't have your text file:
Data = [-360*rand(100,1) 180*rand(100,1)-90 1000*rand(100,1)];

% define the depth levels and colors, for plotting data in different 
% depth ranges with different colors:
depth_levels = [100 300];
colors = [ ...
    1 1 0; ... % yellow
    0 0 1; ... % blue
    1 0 0];    % red

lon=Data(:,1); lon=360+lon;
lat=Data(:,2);
depth=Data(:,3);n=length(depth);

figure(1);clf;axis equal;hold on;

% put -Inf and Inf around depth_levels, to avoid edge effects
depth_levels = [-Inf depth_levels Inf];

% for each depth range ...
for ii = 1:numel(depth_levels)-1
    % get a logical index of the data points in that range
    idx = depth > depth_levels(ii) & depth <= depth_levels(ii+1);
    % and plot them with the corresponding color
    plot(lon(idx),lat(idx), ...
        'LineStyle','none', ...
        'Color',colors(ii,:), ...
        'Marker','o', ...
        'MarkerFaceColor',colors(ii,:));
end

ylabel('latitude (deg)');xlabel('longitude (deg)')
grid minor; 
title('Depth distribution')

Alternatively, you can use scatter with the optional color input:

figure(2);clf;axis equal;hold on;

% initialize a matrix of colors to be used in scatter
c = zeros(size(Data,1),3);

% for each depth range ...
for ii = 1:numel(depth_levels)-1
    % get a logical index of the data points in that range
    idx = depth > depth_levels(ii) & depth <= depth_levels(ii+1);
    % set those rows of c to the corresponding color
    c(idx,:) = colors(ii*ones(nnz(idx),1),:);
end

scatter(lon,lat,[],c,'filled')

ylabel('latitude (deg)');xlabel('longitude (deg)')
grid minor; 
title('Depth distribution')

[Anitha Limann]

Thank you for your answer. This is a great help.

[Anitha Limann]

Could you please tell me if it is possible to get a colorbar for this?

[Voss]

You're welcome!

Yes, you can make a colorbar.

% first, I make up some random data since I don't have your text file:
Data = [-360*rand(100,1) 180*rand(100,1)-90 1000*rand(100,1)];

% define the depth levels and colors, for plotting data in different 
% depth ranges with different colors:
depth_levels = 0:100:1000;
colors = [ ...
    1 1 0; ... % yellow
    repmat([0 0 1],2,1); ... % blue
    repmat([1 0 0],7,1)];    % red

lon=Data(:,1); lon=360+lon;
lat=Data(:,2);
depth=Data(:,3);n=length(depth);

figure(1);clf;axis equal;hold on;

depth_levels_centers = (depth_levels(1:end-1)+depth_levels(2:end))/2;
c = zeros(size(Data,1),1);
for ii = 1:numel(depth_levels)-1
    idx = depth > depth_levels(ii) & depth <= depth_levels(ii+1);
    c(idx,:) = depth_levels_centers(ii);
end

scatter(lon,lat,[],c,'filled')

ylabel('latitude (deg)');xlabel('longitude (deg)')
grid minor; 
title('Depth distribution')

set(gca(),'Colormap',colors);
cb = colorbar();
clim([0 1000]);
cb.YLabel.String = 'Depth';

[Anitha Limann]

My colorbar gives me depth values between 0 and 1. I check my depth values. they all are between 0 and 1000. could you please check this error?

[Anitha Limann]

My colorbar gives me depth values between 0 and 1. I checked my depth values. they all are between 0 and 1000. could you please check this error?

I used the first method you posted.

Data=load('Depth.txt','-ascii'); 

lon=Data(:,1); lon=360+lon;
lat=Data(:,2);
depth=Data(:,3);n=length(depth);

dgroup=[100 300 600];
dgroup=[-inf dgroup inf];
colors=[0.8500 0.3250 0.0980;1 1 0;0 1 0;0 0 1];
gray=[0.5 0.5 0.5];

% for each depth range ...
for ii = 1:numel(dgroup)-1
    % get a logical index of the data points in that range
    idx = depth > dgroup(ii) & depth <= dgroup(ii+1);
    % and plot them with the corresponding color
    plot(lon(idx),lat(idx),'o','MarkerSize',5,'MarkerFaceColor',colors(ii,:),'MarkerEdgeColor',gray);
    
end
ylabel('latitude (deg)');xlabel('longitude (deg)')
grid minor; 
title('Depth distribution')

set(gca(),'Colormap',colors);
cb = colorbar();
cb.YLabel.String = 'depth';

[Voss]

Don't forget this line, toward the end:

clim([0 1000]);

Also, I changed some other stuff, to get the colorbar to work, like setting the ColorMap of the axes.

[Anitha Limann]

I am so sorry, When I tried with clim it says,

Unrecognized function or variable

'clim'.

Error in Untitled (line 33)

clim([0 1000]);

I also do not understand 'repmat' function and how to use it. Please help me if you could.

Thank you

[Voss]

Apparently in some versions of MATLAB clim is called caxis, so try

caxis([1 10000]);

Regarding repmat, its purpose in general is to replicate a matrix (or repeat a matrix) in a specified way. In this case, I'm using repmat to build the colormap, which needs to have red repeated 7 times (since red covers depths fro 300 to 1000) and blue repeated 2 times (since blue covers depths from 100 to 300).

repmat

clim/caxis