# generate column array with day in year number for each hour in a year

1 view (last 30 days)
Mayk on 22 Oct 2021
Answered: Mayk on 22 Oct 2021
Dear,
i want a column array with length equal to hours in a year: 365d*24h = 8760
the content of the array should be the number of the day, corresponding with the hours, so:
1,1,1,1,1,..1,2,2...,2,3,3,...,3... - 365,365,...,365. (total length: 8760 values, number 1 should be repeated 24 times, then number 2 repeated 24 times, etc).
How to code this efficiently?
What i tried was a for-loop, but i want to use a more efficient way:
days = zeros(24,1);
all_days = days;
for i = 1:365-1
all_days = [all_days; days+i];
end

KSSV on 22 Oct 2021
r=repmat(0:364,24,1) ;
r=r(:);
Mayk on 22 Oct 2021
wow genius! i did know repmat, but i didn't know that using r=r(:); puts everything in one column!
r = r(:); % this converts matrix into a one column array

Mayk on 22 Oct 2021
using this improvement, my time to run this section of code decrease from:
Elapsed time is 0.002214 seconds.
to
Elapsed time is 0.000130 seconds.
thanks!
measured by puting 'tic' before code and 'toc' at end of code to measure time to run code.

R2019b

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