Calculate mean monthly from daily values

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Angela Bowman 2012-1-26

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https://ww2.mathworks.cn/matlabcentral/answers/27156-calculate-mean-monthly-from-daily-values

评论： frankovaT 2018-9-27

I have a file that is 22281 rows x 5 col. This represents 60 years of daily values. I need to calculate mean monthly values for all years and extract, say, only May, to a new file. The resulting output will be 60 values for mean monthly data for May. This will be to compare col4 to col5 (below).

col1=year
col2=month
col3=day
col4=data1
col5=data2

Please help!

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Answer 1

the cyclist 2012-1-26

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https://ww2.mathworks.cn/matlabcentral/answers/27156-calculate-mean-monthly-from-daily-values#answer_35349

Take a look at the solutions to this question: http://www.mathworks.com/matlabcentral/answers/27088-sort-data-by-day-of-year. You might find some ideas there that help you.

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Answer 2

Kostas 2012-1-26

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在 MATLAB Online 中打开

maybe smt like this could work

suppose you have a matrix called data(22281,5) months are stored in second column

for i=1:12 %loop over months
idx=find(data(:,2)==i); % find all indeces for the specific month
meandata1=mean(idx,4);
meandata2=mean(idx,5);
meandata(i,:)=[i meandata1 meandata2]; %store in a new matrix the mean values per months
end

now you can just find and print in a file the values for the 5th month (May)

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Faisal Amri 2017-11-23

在 MATLAB Online 中打开

I Tried to modify, this what I got and it works for me though I still working to make it better. Hope this helps

k=1
  %Calculating Monthly Average
  for j=1992:2012                                     %Years Looping
      for i=1:12                                      %Months Looping
          idx=find((Data(:,1)==i) & (Data(:,3)==j));  %Find all indeces for the specific month
          meandata1=mean(Data(idx,4),1);
          Monthly_Ave(k,:)=[i,j,meandata1;];          %Store in a new matrix the mean values per month
          k=k+1;
      end
  end