MATLAB: Converting 3D matrix to 2D matrix .

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I have 3D(20*28*8) matrix . want to convert into 2D (20*28) matrix .Where last 8 means three hour interval one day precipitation data . I want to convert it into daily data(sum of three hour interval 8 data into 1 data ). I have used followed code .

cmorph_precip=ncread('267523.cmorph_precip.cmorph.3hr-025deg.20030702.nc','cmorph_precip')
 nd=size(cmorph_precip,3)
 sum_rain=zeros(20,28) 
 for i=1,nd
rain=cmorph_precip(:,:,i)
sum_rain=sum_rain+rain
 end

Best Answer

A = rand(20,28,8) ;
m = mean(A,3) ;

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MATLAB: How to write a LOOP for this case

So again, numbered variables and field names are a bad idea. (see here and here) for the related questions). The whole thing would be simpler if the original cell array was used.

If the original cell array had been kept, the code over the 3 questions could be simplified to:

%using original cell array precips
precip_monthly = cell(size(precips));  %preallocate result cell array
for idx = 1:numel(precips)
    if size(precips{idx}, 3) == 365
        month_lengths=[31 28 31 30 31 30 31 31 30 31 30 31];%non-leap year
    else
        month_lengths=[31 29 31 30 31 30 31 31 30 31 30 31];%leap year
    end
    p_month =mat2cell(precips{idx}, size(precips{idx}, 1), size(precips{idx}, 2), month_lengths);%divide into 1 cell per month
    p_month = cellfun(@(x) sum(x, 3, 'omitnan'), p_month, 'UniformOutput', false); %find mean for each month !!THIS CALCULATE THE SUM!!
    precip_monthly{idx} = cell2mat(p_month);%convert back to 3D array
end

Note that you have written a comment that says find mean for each month but you use the sum function. So either the code or the comment is wrong.

MATLAB: How to summarize this code

You can try to create structure for the data of different years:

for i = 1:length(precips)
    precip.(['y',num2str(i+1981)]) = precips{i,1};
end

Now, if you want to access data with any specific year say 2000. You can just type:

Req_data = precip.y2000;

I hope it helps!

Best Answer

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MATLAB: How to summarize this code

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