MATLAB: Contour plot based on xyz data

contourplot

I have xyz data as attached. X is longitude, y is altitude and z is electron density. For each value of longitude from 75 to 95, I have altitude values of 100 to 2000 with corresponding electron density values for each altitude. I want a colored contour plot with these data. Please help.

Best Answer

Your data are gridded. You only need to reshape them into your ‘X’, ‘Y’, and ‘Z’ matrices:

D = load('data_new.txt');
[Du,D1] = unique(D(:,1));
Dd = diff(D1);
Dr = reshape(D, Dd(1), [], size(D,2));
X = Dr(:,:,1);
Y = Dr(:,:,2);
Z = Dr(:,:,3);
figure
contourf(X, Y, Z)

See the documentation on contourf (link) for details on how to customise it.

Related Solutions

MATLAB: Contour from .xlsx, getting “Z must be at least a 2×2 matrix” error

You first need to convert you z vector into a grid to use contour()

data = xlsread('data.xlsx','Sheet1','A1:C300');
x = data(:,2);
y = data(:,1);
z = data(:,3);
xg = linspace(min(x), max(x), 50);
yg = linspace(min(y), max(y), 50);
[X,Y]=meshgrid(xg,yg);
Z = griddata(x, y, z, X, Y);
contour(X,Y,Z)

MATLAB: Contour plot for given x,y,z


[num,txt,raw] = xlsread('Book1.xlsx') ; 
x = num(:,1) ; 
y = num(:,2) ; 
z = num(:,3) ; 
figure(1)
scatter(x,y,20,z,'filled') ; colorbar
%% Method 1 / Griddata
nx = 500 ; ny = 500 ;
[X,Y] = meshgrid(linspace(min(x),max(x),nx),linspace(min(y),max(y),ny)) ;
Z =griddata(x,y,z,X,Y) ;
figure(2)
contour(X,Y,Z) ;
figure(3)
pcolor(X,Y,Z)
shading interp 
%% Method 2 simple reshaping 
x = unique(x) ; nx = length(x) ;
y = unique(y) ; ny = length(y) ;
Z = reshape(z,ny,nx) ;
figure(4)
contour(x,y,Z)

Best Answer

Related Solutions

MATLAB: Contour from .xlsx, getting “Z must be at least a 2×2 matrix” error

MATLAB: Contour plot for given x,y,z

Related Question