hourly average of multiple column data

Question

navan 2016-5-12

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/283928-hourly-average-of-multiple-column-data

评论： Guillaume 2016-5-12

I have made a code to calculate hourly average of minute data. But it works only for single column. I have multiple column of concentration data. How can i get the desired answers. pls help.

day1hour=hour(date==1);
day1bc=BC(find(hour(date==1)));
maxday1=max(day1hour);
for i=1:max(day1hour)
ll= find(day1hour==i);
    fffff=BC(ll);
    mean_BC_hourly1(i,:)=mean(fffff);
  end

The input datas are:

day  hour   Con 1  con2
1  10  20
1  20  40
2  30  60
2  40  80
3  50  100
3  60  120
3  70  140

The answer expected:

con1avg   con2avg
30
70
120

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Guillaume 2016-5-12

在 MATLAB Online 中打开

Note that none of the find in your code are necessary. They just slow down the processing.

day1bc = BC(hour(date == 1))); %works just as well

Star Strider 2016-5-12

See also: http://www.mathworks.com/matlabcentral/answers/283934-hourly-average-of-multiple-column-data that seems to be an essential duplicate.

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Answer 1

Guillaume 2016-5-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/283928-hourly-average-of-multiple-column-data#answer_221897

编辑：Guillaume 2016-5-12

在 MATLAB Online 中打开

Use accumarray:

m = [1  1  10  20 
     1  1  20  40
     1  2  30  60
     1  2  40  80
     1  3  50  100
     1  3  60  120
     1  3  70  140]
[dayhour, ~, destrow] = unique(m(:, [1, 2]), 'rows');
subs = [repmat(destrow, 2, 1), repelem([1;2], numel(destrow))];
hourlymean = accumarray(subs, reshape(m(:, [3, 4]), [], 1), [], @mean);
array2table([dayhour, hourlymean], 'VariableNames', {'day', 'hour', 'con1avg', 'con2avg'})

Or the new split apply workflow introduced in R2015b

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navan 2016-5-12

编辑：navan 2016-5-12

Wow. Wonderful. Thanks a ton Guillaume. It is what i wanted really. It is a great help. thank you once again :) But if i have around 10 concentration how should i modify the code ?

Guillaume 2016-5-12

在 MATLAB Online 中打开

colstoaverage = 3:12;
subs = [repmat(destrow, numel(colstoaverage), 1), repelem((1:numel(colstoaverage))', numel(destrow))];
hourlymean = accumarray(subs, reshape(m(:, colstoaverage), [], 1), [], @mean)

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