Question

I have lat, lon, data for a month data, I am working them to put on a regular uniform grid (2 deg) without interpolation (bining). I am getting an error : index exceed dimensions”

I have lat, lon, var are in column matrix, these are obtained from multiple files of 1 month (thousands of rows).Here I am getting an error with X(zind(k,1),zind(k,2))=mean(zind(ind)); where the index exceed dimensions. Thanks for the help,

where x=lat, y=lon, z=var

   % make grid for scattered lat, lon, var
    data=load('mydata.txt')
    x=data(:,1);
    y=data(:,2);
    z=data(:,3);
    %make a grid with 2 degree
    cellsize=2;
    minx=-90;
    maxx=90;
    miny=-180;
    maxy=180;
    xi=(minx:cellsize:maxx);
    yi=(miny:cellsize:maxy);
    [X,Y]=meshgrid(xi,yi);
    [m,n]=size(X);
    %populate grid and make average
    xind=floor((x-minx)./cellsize)+1;
    yind=floor((y-miny)./cellsize)+1;
    zind=unique([yind,xind],'rows');
    Z=ones(m,n).*NaN;

    for k=1:length(zind)
    ind=find(xind==zind(k,2)&...
     yind==zind(k,1)==1);
  X(zind(k,1),zind(k,2))=mean(zind(ind));
 end
    %make a plot
    figure;
    axis([-180 180 90 -90]);
    imagesc(xi,yi,Z);
    **********************

Answer 1

First:

ind=find(xind==zind(k,2)&...
     yind==zind(k,1)==1);

I don’t think the ==1 should be there.

Second, I think your error comes from the mean(zind(ind)): You don’t want the mean of zind, being indices of unique (y,x) indices. You want the mean of z:

X(zind(k,1),zind(k,2))=mean(z(ind));  % changed last zind -> z