How would you upscale gridded data?

Hi

I have a 2-d 12km dataset that I would like to convert to 32km gridded resolution. Just wondering how you would approach this? I have written a for loop seen here: http://pastebin.com/6iq97HyR, but it takes way too long to complete(~1.5 weeks)

Thanks

for lo = 20:91
    for la = 1:101
        tmplat = latsmall(lo,la);
        tmplon = lonsmall(lo,la);
        f = find(min((latNLDAS(:)-tmplat).^2+(lonNLDAS(:)-tmplon).^2)==((latNLDAS(:)-tmplat).^2+(lonNLDAS(:)-tmplon).^2));
        y = floor(f/224)+1;
        y = y(1);
        x = mod(f,224);
        x = x(1);
        for yr = 1:15
            tic;
            for mo = 1:5
                fprintf(' lo %d la %d yr %d mo %d \n',lo,la,yr+1994,mo);
                for dy=1:31
                    pptNL(yr,lo,la,mo,dy)= nan;
                    if (mo == 2 || 5) && (dy==31)
                        continue;
                    else
                        date = [num2str(mo+4) '/' num2str(dy) '/' num2str(1994+yr)];
                        if (x-2<=0) || (y-2<=0) || (x-2>224) || (y-2>464) ||...,
                                (x-1<=0) || (y-1<=0) || (x-1>224) || (y-1>464) ||...,
                                (x-0<=0) || (y-0<=0) || (x-0>224) || (y-0>464) ||...,
                                (x+1<=0) || (y+1<=0) || (x+1>224) || (y+1>464) ||...,
                                (x+2<=0) || (y+2<=0) || (x+2>224) || (y+2>464)
                            continue
                        else
                            pptNL(yr,lo,la,mo,dy)= nanmean...,
                                ([PRECIP(x-2,y+2,datevec2doy(datevec(date)))...,
                                PRECIP(x-2,y+1,datevec2doy(datevec(date)))...,
                                PRECIP(x-2,y+0,datevec2doy(datevec(date)))...,
                                PRECIP(x-2,y-1,datevec2doy(datevec(date)))...,
                                PRECIP(x-2,y-2,datevec2doy(datevec(date)))...,
                                PRECIP(x-1,y+2,datevec2doy(datevec(date)))...,
                                PRECIP(x-1,y+1,datevec2doy(datevec(date)))...,
                                PRECIP(x-1,y+0,datevec2doy(datevec(date)))...,
                                PRECIP(x-1,y-1,datevec2doy(datevec(date)))...,
                                PRECIP(x-1,y-2,datevec2doy(datevec(date)))...,
                                PRECIP(x,y+2,datevec2doy(datevec(date)))...,
                                PRECIP(x,y+1,datevec2doy(datevec(date)))...,
                                PRECIP(x,y,datevec2doy(datevec(date)))...,
                                PRECIP(x,y-1,datevec2doy(datevec(date)))...,
                                PRECIP(x,y-2,datevec2doy(datevec(date)))...,
                                PRECIP(x+1,y+2,datevec2doy(datevec(date)))...,
                                PRECIP(x+1,y+1,datevec2doy(datevec(date)))...,
                                PRECIP(x+1,y+0,datevec2doy(datevec(date)))...,
                                PRECIP(x+1,y-1,datevec2doy(datevec(date)))...,
                                PRECIP(x+1,y-2,datevec2doy(datevec(date)))...,
                                PRECIP(x+2,y+2,datevec2doy(datevec(date)))...,
                                PRECIP(x+2,y+1,datevec2doy(datevec(date)))...,
                                PRECIP(x+2,y+0,datevec2doy(datevec(date)))...,
                                PRECIP(x+2,y-1,datevec2doy(datevec(date)))...,
                                PRECIP(x+2,y-2,datevec2doy(datevec(date)))...,
                                ]);
                        end
                    end
                end
            end
        end
    end
end

[Oleg Komarov]

I added the code, next time please consider formatting it into the post as I did.

Have you tried running the profile on a small data set to identify the bottlenecks?

Preallocating pptNL would help drastically.

Also, as is, contributors cannot help you because you didn't supply some sample inputs to run your code with.

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

What is latsmall and lonsmall? (function or variable?)