scatter plotting color coded

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!

[Sara]

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?

[shobhit mehrotra]

I want to know how to create a color coded scatter plot, with lat and lon on the axis and ch4 on the spectrum. Thanks

Answer 1

[Image Analyst]

Use scatter() - with that function you can control the color and size of every marker.

Answer 2

[Alfonso Nieto-Castanon]

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.