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How to associate and color points based on distance or search radius and contour them?

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Abdelrahman Abdeltawab
Abdelrahman Abdeltawab on 26 Nov 2016
Commented: Xel Ch on 27 Jun 2018
I have scatter plot shown in first image
what is the best method to reach the result in second image?

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Answers (1)

Jose Lara
Jose Lara on 5 Dec 2016
Abdelrahman, if you know the temperature for each of the coordinate given, you could create your own gradient of color.  If you have a matrix with the coordinates, for example:
coords = [1 2 3 4 5 6 7 8; 2 5 7 8 9 9 0 3];
then you may iterate through each point and designate it's own color depending on the resulting temperature. If the equation for the temperature is as follows:
T = x^2 +y/2 +1;
using a for loop, you can iterate through each point and plot with the correct color. Example code is shown below:
for i = 1:8 %number of coordinates
    hold on
    xi = coords(1,i);
    yi = coords(2,i);
    T =  xi^2 + yi/2 +1;
    if T > 10;
         plot(xi,yi,'ko')
    elseif (T<10) && (T>8)
         plot(xi,yi,'bo')
    elseif (T<8) && (T<4)
         plot(xi,yi,'ro')
    else
         plot(xi,yi,'go')
where the third argument of the ''plot'' function will be the color of the point and the marker type. You may separate the temperatures with more colors by using a RGB color values such as [1 0 0] for red and [1 1 1] for white. 
Check out the following link for more information on the ''plot'' function: http://www.mathworks.com/help/matlab/ref/plot.html

  2 Comments

Abdelrahman Abdeltawab
Abdelrahman Abdeltawab on 6 Dec 2016
Thanks alot Jose, but my what i wanted is for each point in the scatter find the nearby points and cluster them or highlight them
Xel Ch
Xel Ch on 27 Jun 2018
Hi Abdelrahman. I am looking to do something similar in Matlab, so was wondering if you were ever able to get this issue resolved? And if so, what did you do? Thank you!

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