contour plot using x y z data

I want to make a colour filled beautiful contour map using my data attached and want to write A B C D E F G H on the map itself at the scatter point

dt y x z

A 31.53 77.95 0.112

B 31.40 78.35 0.032

C 31.66 78.03 -0.001

D 31.48 77.75 -0.092

E 32.28 78.45 -0.113

F 31.99 76.42 -0.184

G 31.64 77.34 -0.016

H 32.50 75.62 -0.121

i tried contourf(x,y z)..but getting errors.

please suggest a solution.

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/fileexchange/38858-contour-plot-for-scattered-data

However, that uses patch() to put in the contours, and is not compatible with using clabel(), so you would have to text() in appropriate places.

See https://www.mathworks.com/help/matlab/math/interpolating-scattered-data.html#bsovi2t for a different approach which is compatible with clabel()

If you do use clabel() you will not be able to directly control the text. However you can record the first output of clabel(), which will be the handles to the text objects, and you can then modify the String property of those text objects.

[Walter Roberson]

data = {
    'A'  31.53  77.95   0.112
    'B'  31.40  78.35   0.032
    'C'  31.66  78.03  -0.001
    'D'  31.48  77.75  -0.092
    'E'  32.28  78.45  -0.113
    'F'  31.99  76.42  -0.184
    'G'  31.64  77.34  -0.016
    'H'  32.50  75.62  -0.121};
dt = data(:,1);
y = vertcat(data{:,2});
x = vertcat(data{:,3});
z = vertcat(data{:,4});

N = 20;
[X, Y] = meshgrid(linspace(min(x)-0.2, max(x)+0.2, N), linspace(min(y)-0.2, max(y)+0.2, N));
F = scatteredInterpolant(x, y, z);
Z = F(X, Y);
[C,h] = contour(X, Y, Z);
clabel(C)
text(x, y, dt);
colorbar()

[Richard Sanders]

Hi there,

I know this is a pretty old post but I've been doing something similar and am not very familiar with Matlab yet, hopefully you can still help me. Is it possible to have the space between the lines filled with the according colours? Also possibly important to note that I'm working with a fairly large dataset (almost 2000 values for x, y and z each).

[Voss]

@Richard Sanders To have a filled contour, you can use contourf() in place of contour():

data = {
    'A'  31.53  77.95   0.112
    'B'  31.40  78.35   0.032
    'C'  31.66  78.03  -0.001
    'D'  31.48  77.75  -0.092
    'E'  32.28  78.45  -0.113
    'F'  31.99  76.42  -0.184
    'G'  31.64  77.34  -0.016
    'H'  32.50  75.62  -0.121};
dt = data(:,1);
y = vertcat(data{:,2});
x = vertcat(data{:,3});
z = vertcat(data{:,4});
N = 20;
[X, Y] = meshgrid(linspace(min(x)-0.2, max(x)+0.2, N), linspace(min(y)-0.2, max(y)+0.2, N));
F = scatteredInterpolant(x, y, z);
Z = F(X, Y);
[C,h] = contourf(X, Y, Z);
clabel(C)
text(x, y, dt);
colorbar()