MATLAB: How to plot a temperature in xy axis (2D temperature contour)

plot

Hi i am new to matlab and I wanted to plot the temperature in x,y as shown above. I have set of data in excel file.
I've tried using surf plot but i keep getting errors "Z must be a matrix, not a scalar or vector."

Best Answer

  • The surf function expects a matrix, so you will have to convert your linear data to a matrix. The accumarray function is a very flexible tool and worth exploring if you've never seen it before. A general advice would be to read the documentation for functions you are trying to use, and read the related functions linked at the bottom if you think it doesn't quite do what you need.
    The code below should result in a plot you expect. Play around with the syntax for surf and colorbar to get the exact output you want.
    %read data
    filename='Temperature.csv';
    Data = csvread(filename,6,0);%skip 6 header lines
    X_data=Data(:,1);
    Y_data=Data(:,2);
    T_data=Data(:,4);
    %create grid
    [x,~,xi]=unique(X_data);
    [y,~,yi]=unique(Y_data);
    subs=[xi yi];%use the indices instead of values as coordinates
    val=T_data;
    M=accumarray(subs,val,[],[],NaN);%fill missing with NaN
    [X,Y]=ndgrid(x,y);%generate the grid surf() expects
    %create plot
    figure(1),clf(1)
    surf(X,Y,M)
    %overlay the raw data points (optional)
    % hold on
    % plot3(X_data,Y_data,T_data,'*')
    % hold off
    view(0,90),xlabel('x'),ylabel('y')
    colorbar