How to calculate the accumulated rainfall value of 1, 2, 3, 4, 5, 6 and 7 days.

I need to calculate the cumulative rainfall of 1, 2, 3, 4, 5, 6 and 7 days and extract the annual maximum of each year (after accumulation). I have historical series of precipitation with a great amount of years organized as follows: day, month, year, precipitation [mm], each in a column. I tried using the code below but it did not work.

%% Import Precipitation Data
RainMatrix = importdata ('data.txt');

% Identifies the first and last year of the series
First_Year  = RainMatrix(1,3);
Last_Year   = RainMatrix(end,3);

% Measuring the Data Series Size;
T                  = length(unique(RainMatrix(:,3)));

P  = 2;                                                                   % Time Step, P = 1, 2, 3, 4, 5, 6 and 7 days
k   = 1;                                                                  % Counter
for ii = 1 : (T-1)
    Year               = find(RainMatrix(:,3) == First_Year);             % Identifies the year
    RainMatrix         = RainMatrix(Year(:,1),:);                         % Cut the year
    n                  = length(RainMatrix);                              % Dimension of Cut Out Data
    for i = P : P : n
        Rainfall(k,1)  = sum(RainMatrix(i-P+1:i,4));                      % Cumulative rainfall of "P" days
        k = k+1;
        [x, y]         = ismember(max(Rainfall(:,1)),Rainfall(:,1));      % Find the Maximum Value of the Series
        MaxAnual(ii,1)           = Rainfall(y);                           
    end
    First_Year         = First_Year + 1;
    Rainfall           = [];
end

[darova]

You forgot to attach data

[Walter Roberson]

When you do cumulative for a particular number of days, are you wanting to do distinct windows or sliding windows? d1, d2, d3, d4 -> (d1+d2), (d3+d4) or instead (d1+d2), (d2+d3), (d3+d4) ?

[GA]

Sorry. I edited the question and added an example

[GA]

I wish this way: (d1 + d2), (d3 + d4) ...

Answer 1

[David Wilson]

Here is my solution:

I notice that you've got few NaNs for about a year and a half. Your last year is also incomplete.

I isolated each year, and then reshaped the data in blocks of 1,2, ... 7. I dropped a few days at the end of the year if they were not exact multiples. I then summed the cols, and then took the max and stored it in an array.

%% Import Precipitation Data
RainMatrix = importdata('data.txt');
% Identifies the first and last year of the series

yr =  RainMatrix(:,3); % years 
yr1 = yr(1); yr_end = yr(end); 
Raincum = NaN(yr_end-yr1+1,7); % placeholder 

k=0; 
for i=yr1:yr_end % scan each year 
    k=k+1; 
    idx = find(yr == i); 
    yri = yr(idx); r  = RainMatrix(idx,4); nr = length(r); 
    length(yri); % check should be 365 or 366 for full years 
    Raincum(k,1) = max(r); 
    for j=2:7 
        rv = r(1:nr - mod(nr,j)); 
        r2 = reshape(rv,j,length(rv)/j);
        r2 = sum(r2); 
        Raincum(k,j) = max(r2); 
    end 

end 

%% 
yrs = [yr1:yr_end]'; 
plot(yrs,Raincum)
legend('1','2','3','4','5','6','7')

[GA]

Thank you !! Worked perfectly