calculate the annual discharge over several years
2 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Maria Mateus
am 29 Okt. 2013
Kommentiert: Maria Mateus
am 29 Okt. 2013
Hello,
I have a time series dataset that consists of daily discharge (Q) data from 1915-2006. My matrix: the first column is the year, the second is the month, the third is the day and the fourth column is the data of interest (Q). I need to calculate the mean annual discharge for each year and then arrange the data from the smallest Q to largest Q but knowing to which year that Q belongs.
- Year Month day Q
- 1915 10 1 2.13E+02
- 1915 10 2 2.89E+02
- 1915 10 3 8.10E+02
- ...
- ...
- 2006 12 31 2.20E+04
I am very new at Matlab and even though I found some similar examples online I can't figure this out. Any help will be really appreciated.
Thanks!
2 Kommentare
Akzeptierte Antwort
Cedric
am 29 Okt. 2013
Bearbeitet: Cedric
am 29 Okt. 2013
EDIT after you edited the question: it seems that there are 4 columns and not 2, and the discharge is in column4. I am updating my answer accordingly.
Here is an example
data = [1915, 7, 1, 6; ...
1915, 10, 3, 8; ...
1915, 12, 8, 7; ...
1916, 4, 22, 3; ...
1916, 7, 13, 2] ;
% - Get unique years and assign IDs starting at 1.
years = unique( data(:,1) ) ;
yearId = data(:,1) - min( data(:,1) ) + 1 ;
% - Compute Q mean per year.
Qmean = accumarray( yearId, data(:,4), [], @mean ) ;
% - Sort Qmean and get corresponding years.
[Qmean_sorted, ix] = sort( Qmean ) ;
years_sorted = years(ix) ;
Running this, you get
>> Qmean
Qmean =
7.0000
2.5000
>> Qmean_sorted
Qmean_sorted =
2.5000
7.0000
>> years_sorted
years_sorted =
1916
1915
2 Kommentare
Weitere Antworten (1)
sixwwwwww
am 29 Okt. 2013
Dear Maria, here is the code for required functionality:
ID = fopen('filename.txt');
data = textscan(ID, '%f%f%f%f');
fclose(ID);
year = data{1};
interest = data{4};
count = 1;
i = 1915:2006;
avg = zeros(length(i), 2);
for i = 1915:2006
ind = find(ismember(year, i));
avg(count, 1) = i;
avg(count, 2) = sum(interest(ind)) / length(ind);
count = count + 1;
end
avg = sortrows(avg, 2);
disp(avg)
I hope it helps. Good luck!
Siehe auch
Kategorien
Mehr zu Logical finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!