how to calculate mean and stdev of unequally intervalled data based on different time?

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Md. Moklesur Rahman
Md. Moklesur Rahman 2012-10-26
Hello every one,
I am trying to calculate the hourly mean and standard deviation of my five minutes data. The number of data should be 12 in one hour but unfortunately due to data missing sometimes less than 12 and even only one data.
My data format in the file is as follows (two consecutive data set):
7/16/2012 6:40 2.20E+03
7/16/2012 6:45 1.87E+03
7/16/2012 6:50 1.83E+03
7/16/2012 6:55 1.94E+03
7/16/2012 7:00 1.86E+03
7/16/2012 7:05 1.74E+03
7/16/2012 7:10 1.78E+03
7/16/2012 7:15 1.65E+03
7/16/2012 7:20 1.77E+03
7/16/2012 7:25 1.74E+03
7/16/2012 7:30 1.82E+03
7/16/2012 7:35 1.65E+03
7/16/2012 8:40 1.68E+03
7/16/2012 8:45 1.61E+03
7/16/2012 8:50 1.78E+03
7/16/2012 8:55 1.67E+03
7/16/2012 9:00 1.66E+03
7/16/2012 9:05 1.66E+03
7/16/2012 9:10 1.71E+03
7/16/2012 9:15 1.65E+03
7/16/2012 9:20 1.73E+03
7/16/2012 9:25 1.66E+03
7/16/2012 9:30 1.70E+03
7/16/2012 9:35 1.64E+03
After calculating the mean and stdev, I want to get the output in a new array as follows:
start-time End-time Mean stdev
I will highly appreciate any of your helping hand. Thank you very much in advance.
Rahman

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回答（2 个）

Matt J
Matt J 2012-10-26
编辑：Matt J 2012-10-26
Use HISTC to bin the data into hourly intervals.
Then use ACCUMARRAY to get the mean and std over each bin.
Andrei Bobrov
Andrei Bobrov 2012-10-26
编辑：Andrei Bobrov 2012-10-26
Your data in file yourtext.txt:
7/16/2012 6:40 2.20E+03
7/16/2012 6:45 1.87E+03
7/16/2012 6:50 1.83E+03
7/16/2012 6:55 1.94E+03
7/16/2012 7:00 1.86E+03
7/16/2012 7:05 1.74E+03
7/16/2012 7:10 1.78E+03
7/16/2012 7:15 1.65E+03
7/16/2012 7:20 1.77E+03
7/16/2012 7:25 1.74E+03
7/16/2012 7:30 1.82E+03
7/16/2012 7:35 1.65E+03
7/16/2012 8:40 1.68E+03
7/16/2012 8:45 1.61E+03
7/16/2012 8:50 1.78E+03
7/16/2012 8:55 1.67E+03
7/16/2012 9:00 1.66E+03
7/16/2012 9:05 1.66E+03
7/16/2012 9:10 1.71E+03
7/16/2012 9:15 1.65E+03
7/16/2012 9:20 1.73E+03
7/16/2012 9:25 1.66E+03
7/16/2012 9:30 1.70E+03
7/16/2012 9:35 1.64E+03
f1 = fopen('yourtxt.txt'); c = textscan(f1,'%s %s %f'); fclose(f1);
[Y M D H] = datevec(strrep(strcat(c{1},'_',c{2}),'_',' '));
[a,cc,cc] = unique([Y M D H],'rows');
a1 = num2cell(a,1);
daten = cellstr(datestr(datenum(a1{1:3},a1{4}+1,0, 0)));
data = ...
cell2mat(cellfun(@(x)[mean(x),std(x)],accumarray(cc,c{3},[],@(x){x}),'un',0));
out = [daten, num2cell(data)];
ADD
f1 = fopen('yourtxt.txt'); c = textscan(f1,'%s %s %f'); fclose(f1);
sdate = strrep(strcat(c{1},'_',c{2}),'_',' ');
[~,~,~, H MM] = datevec(sdate);
t = abs(diff([H MM]*[1;1/60]) - 5/60) > eps(100);
dc = accumarray(cumsum([1;t]),c{3},[],@(x){x});
datan = num2cell(cell2mat(cellfun(@(x) [mean(x), std(x)],dc,'un',0)));
ii = find(t);
out = [sdate([1;ii]) sdate([ii+1;end]) datan];
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