Thread Subject: resizing database

Could someone please help me out...

I have a very large database and according to certain critirias I'm only selecting a part of it and renaming it in order to do my calculations faster.
So for example I have a database of 30200x200 where one of the columns represents time. Through a for and an if loop I have a new database of 500x200 (say only looking at half a day's data if a series of criterias are fullfilled).

My problem is that when doing this, my new database of 500x200 has a series of rows with zeros values (created by the if and for loops - these were not there beforehand). In reality my actual data is 350x200.
To remove the zeros I have another loop. However, as I have to repeat this several times, this takes a while to compute.

Is there anyway I can speed the process up?

Cheers

It might help if you posted some code... :-)

Sorry thought it would be easier with words. Anyway, here goes...

The script starts by seperating data into days and then runs if certain conditions are fullfilled (I.E. if the data has a full days worth of info - stating at measurement 1 and finishing at measurement 8640)

for v=1:((length(Loc))-1);
if A((Loc(v,1)),2)==1
if A((Loc(v+1,1))-1,2)==8640

% seperating the database into smaller ones
            for m=1:2975
                for n=1:200
                    if A(m,39)==1
                        Cloudy(m,n)=A(m,n);
                    elseif A(m,39)==2
                        Rainy(m,n)=A(m,n);
                     elseif A(m,39)==3
                        Sunny(m,n)=A(m,n);
                     end
                end
            end

% removing the zeros
s=size(Day1);
Down=s(1,1);
Across=s(1,2);
           for m=1:Down
               for n=1:Across
                   if Day1(m,1)~= 0
                       Day1(m,n)=Day1(m,n);
                   else
                       Day1(m,n)=NaN;
                   end
               end
           end
           Day1(any(isnan(Day1),2),:) = [];
%This is obviously repeated for every smaller database

.... % remaning of calculations to be done
end
end


I hope this makes things clearer...