# Increment dates using for loop

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CM on 9 Feb 2019
I'm trying to fill a variable sized datetime array. I then want the declared datetime value to fill the first 3 elements before incrementing by one to fill the next three.This process repeats until the desired sized element is reach. See current output & desired output.
Code:
samples = input("Number of Samples to Generate: ");
DateBuilt = repmat(datetime(0,0,0),samples,1);
t = datetime(2018,1,1);
DateBuilt(1) = t
for i=1:samples
if i <= 3
DateBuilt(i) = t;
else
t = t + 1;
DateBuilt(i) = t;
end
Current Output:
Number of Samples to Generate: 14
DateBuilt =
14×1 datetime array
01-Jan-2018
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
30-Nov--0001
Desired Output:
Number of Samples to Generate: 14
DateBuilt =
14×1 datetime array
01-Jan-2018
01-Jan-2018
01-Jan-2018
02-Jan-2018
02-Jan-2018
02-Jan-2018
03-Jan-2018
03-Jan-2018
03-Jan-2018
04-Jan-2018
04-Jan-2018
04-Jan-2018
05-Jan-2018
05-Jan-2018

CM on 9 Feb 2019
I apologise. I realized that I asked the wrong question when I saw the answer. I edited the question to reflect what outcome I am hoping for
madhan ravi on 9 Feb 2019
Why in your desired output the last date has only repeated twice , any reason for it?
CM on 9 Feb 2019
Yes. The user input (*see “samples“ variable in code) determines the number of elements in the datetime array. The first element of array is filled with a datetime. The loop then continues to fill the 2nd and 3rd elements before incrementing by 1 day. the loop then proceeds to fill the 4th, 5th, and 6th elements before incrementing again and repeating the process for the next three elements This continues until the user defined size is reached. Repeating the last date only twice is my attempt to show that the loop stops based on an arbitrary number entered by the user.

Eric Sofen on 9 Feb 2019
Are there any other calculations being done in the loop body of your actual code? If not, this can be done without looping:
samples = input("Number of Samples to Generate: ");
days = floor((0:samples-1)./3)'+1;
dt = datetime(2018,1,days);
If you do really need to loop for some other reason, there are things that need to change in your code:
1) It's missing and end to the conditional block.
2) t = t+1 ends up incrementing the day every iteration.
samples = input("Number of Samples to Generate: ");
DateBuilt = repmat(datetime(0,0,0),samples,1);
t = datetime(2018,1,1);
DateBuilt(1) = t;
for i=1:samples
DateBuilt(i) = t+days(floor((i-1)/3));
end

Stephen Cobeldick on 9 Feb 2019
>> D = datetime('01-Jan-2018');
>> N = 14;
>> G = 3;
>> V = D + caldays(0:ceil(N/G)-1).';
>> V = repelem(V,G);
>> V = V(1:N)
V =
01-Jan-2018
01-Jan-2018
01-Jan-2018
02-Jan-2018
02-Jan-2018
02-Jan-2018
03-Jan-2018
03-Jan-2018
03-Jan-2018
04-Jan-2018
04-Jan-2018
04-Jan-2018
05-Jan-2018
05-Jan-2018