MATLAB Examples

C2xyz

C2XYZ returns the x and y coordinates of contours in a contour matrix and their corresponding z values. C is the contour matrix given by the contour function.

Contents

Syntax

[x,y] = C2xyz(C)
[x,y,z] = C2xyz(C)

Description

[x,y] = C2xyz(C) returns x and y cell arrays of coordinates of contours in a contour matrix C.

[x,y,z] = C2xyz(C) also returns corresponding z values as double.

Example

Given a contour plot, you want to know the (x,y) coordinates of the contours, as well as the z value corresponding to each contour line.

C = contour(peaks);
[x,y,z] = C2xyz(C);

This returns 1 x numberOfContourLines cells of x values and y values, and their corresponding z values are given in a 1 x numberOfContourLines array. Let's pick out all the x, y locations where z = 0, and make that contour line a heavy black line:

hold on; % Allows plotting atop the preexisting peaks plot.

for n = find(z==0); % only loop through the z = 0 values.
    plot(x{n},y{n},'k','linewidth',2)
end

And let's make all the z = -2 lines red and dotted:

for n = find(z==-2) % now loop through the z = -2 values.
    plot(x{n},y{n},'r:','linewidth',2)
end

Author Info

Created by Chad Greene, of the University of Texas Institute for Geophysics, August 2013. Updated August 2014.