Trying to select multiple sections in an array where the sections are separated by constant size

Let's say that I have an array of size 24, i.e arr=zeros(1,24). Now, let's say that I wan't to set indices [5,6,7,8] and [13,14,15,16] and [21,22,23,24] to 1. So how can I address these array sections without loops? I know that I can write: arr([5:8, 13:16, 21:24]) by hand, but what if the array size is unknown, and I wan't to write it in compact way. Thanks

Answer 1

[Stephen23]

>> arr = zeros(8,3); % or use reshape
>> arr(5:8,:) = 1;
>> arr = reshape(arr,1,24)
arr =
   0   0   0   0   1   1   1   1   0   0   0   0   1   1   1   1   0   0   0   0   1   1   1   1

Or

>> arr = repmat([0,0,0,0,1,1,1,1],1,3)
arr =
   0   0   0   0   1   1   1   1   0   0   0   0   1   1   1   1   0   0   0   0   1   1   1   1

[Omer Sholev]

wow quite, simple. thanks