Contour plot in hexagon form

I have some data for a evenly distributed grid inside a hexagon. I would like to do a contour plot which will look like this:

The data I am trying to plot is uploaded in a MAT file here. Here x and y are the horizontal and vertical values of coordinates respectively.

The plot of the coordinates looks like this:

What I have tried to do is given below,

clearvars;

load('data.mat');

[X,Y]= meshgrid(x, y);

lx=length(X);

Z= zeros(lx,lx); % initializing matrix
nopoints=length(x);

count=1;
for ix=1:lx

      for iy=1:lx

          if (count <= nopoints)

              if(X(ix,iy)==x(count) && Y(ix,iy)==y(count))

                  Z(ix,iy)=z(count);

                  count = count+1;

              else

                  Z(ix,iy) = NaN;

              end

          else
              Z(ix,iy)= NaN;
          end

      end

end

figure;
contour(X,Y,Z);

Unfortunately the plot shows nothing like the first image. With data cursor I can see there are discrete data points but no contour plot. Am I missing something?

Any help regarding this is greatly appreciated. :)

[KSSV]

why dont you attach file here? Going to dropbox logging in is head ache...

[Protik Das]

You can download the file without logging in. Anyway I updated the file.

Answer 1

[Kelly Kearney]

Take a look at the sparsity pattern of the matrix you built to represent your grid:

spy(~isnan(Z))

I don't entirely follow the logic of your code, but it's definitely not gridding the data like you want. The easiest way to do this is with scatteredInterpolant:

f = scatteredInterpolant([x y], z, 'nearest', 'none');
[xg, yg] = meshgrid(unique(x), unique(round(y,2))); 
zg = f(xg,yg);

scatter(x,y,[],z);
hold on;
contour(xg,yg,zg);