scatter plotting color coded
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I have question regarding creating a scatter plot with three variables (lat, lon, ch4). They are all vectors of the same length. I want to plot lon and lat on the x and y axis and show ch4 color coded.
attached is an image of what im trying to create
Thanks!
2 Comments
Sara
on 17 Jul 2014
What do you want to know? How to select only certain indexes in an array like:
index = 12000:34000;
scatter(lat(index), lon(index),[],ch4(index))
or how to find index?
Answers (2)
Image Analyst
on 18 Jul 2014
Use scatter() - with that function you can control the color and size of every marker.
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Alfonso Nieto-Castanon
on 18 Jul 2014
Edited: Alfonso Nieto-Castanon
on 18 Jul 2014
perhaps something along these lines:
% your data (assuming column vectors)
lat = convn(randn(1e3,1),hanning(100));
lon = convn(randn(1e3,1),hanning(100));
ch = convn(randn(1e3,1),hanning(100));
% plot one line for each pair of consecutive points
h = plot([lat(1:end-1) lat(2:end)]',[lon(1:end-1) lon(2:end)]','-');
% decide the color of each line
cmap = jet(128);
color = convn(ch,[1;1],'valid');
color = (color-min(color))/(max(color)-min(color));
color = cmap(round(1+color*127),:);
% assign colors
for n = 1:numel(h),
set(h(n),'color',color(n,:));
end
You could get more sophisticated and use patches instead of lines (this works better when your points are far apart because it allows you to smoothly interpolate the color between two points), or simpler and plot individual dots instead of lines (this works just fine if your points are very close and do not have to worry about connecting the points) depending on your particular dataset.
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