Find the maximum 5 day total in a year

Dear all,

I have data from 1992-2020. For each year, I want to find the maximum 5 day total.

Steps taken:

1. Introduce condition that if the year is a leap year, I should only estimate until 365 days. 366 days is not divisible by 5.
2. Sum every 5 days in a year.
3. Find the maximum sum in a year.

load('Data.mat');

% % Case A: What I want in simpler terms.
a  = P_3(1:366);
b  = P_3(367:731);

if length(a) == 366
    for i = 1:5:length(a)-1
        s1(i) = sum(a(i:i+4));
    end
end

if length(b) == 365
    for i = 1:5:length(b)
        s2(i) = sum(b(i:i+4));
    end
end
s1a = max(s1);
s2a = max(s2);

% % Case B: What I have tried to implement.
y3 = P_3;
for j = 1:size(t1,2)
    a = y3(t1(j):t2(j));
    if length(a) == 366
        for k = 1:5:length(a)-1
            sa1(k,:) = max(sum(a(k:k+4)));
        end
    else 
        for k = 1:5:length(a)
            sa1(k,:) = max(sum(a(k:k+4)));
        end
    end
end
sa2 = max(sa1);

However, case B does not give me the desired results. It only returns the maximum 5 day total of the last year, not all years. How do I resolve this problem? Is it also possible to replicate the same thing without using for loops and if statement?

Thank you very much.

[Star Strider]

I do not see any datetime or other time vector associated with ‘P_3’.

[Eli]

Hi @Star Strider, the number of days representing the start and end of each year are represented by the matrices t1 and t2.

Answer 1

[KSSV]

% create time stamps from 1992 to 2020
thedates = (datetime(1992,1,1):days(1):datetime(2020,12,31))' ;
idx = thedates.Day==29 & thedates.Month==2 ;  % get the logicaL indices of 29th day of Feb in leap years 
% Remove the Feb 29 the values from the data 
data = P_3 ; 
data(idx) = [] ; 
% reshape the data to each year 
data = reshape(data,[],length(data)/365) ;
% sum for every five days for each year by reshaping 
[r,c] = size(data);
nlay  = 365/5;
out   = permute(reshape(data',[c,r/nlay,nlay]),[2,1,3]);
thesum = squeeze(sum(out,1)) ; 
iwant = max(thesum,[],2)  % get the maximum