Create array with random integers, skipping by a certain interval each time

Hi,

I would like help writing a piece of code that will create a 1 x n array, of which each number is a random integer within a user-defined range (magic_number), but after each number, the range is shifted by an interval equal to magic_number. I also want the total size of the array to equal magic_number.

For example:

magic_number = 10;

resulting_array = [randi(magic_number) ...
                   (randi(magic_number) + magic_number) ...
                   (randi(magic_number) + 2*magic_number) ...
                   (randi(magic_number) + 3*magic_number) ...
                   (randi(magic_number) + 4*magic_number) ...
                   (randi(magic_number) + 5*magic_number) ...
                   (randi(magic_number) + 6*magic_number) ...
                   (randi(magic_number) + 7*magic_number) ...
                   (randi(magic_number) + 8*magic_number) ...
                   (randi(magic_number) + 9*magic_number)];

resulting_array

One possible answer for resulting_array would thus be: 4 16 23 39 41 60 67 79 88 100

The above code does almost what I'm looking for, but I want it to be fully automated. Changing magic_number will change the random integer range and the interval shift, but not the total size of the array. For example, if magic_number was changed to 9, I would have to delete the last line. If it was changed to 11, I would have to add a line, etc.

I considered randperm, but as far as I know there is no way to specify jumping intervals like this with randperm. I also considered the use of a for loop, but I couldn't quite get there.

Any help is greatly appreciated!

Answer 1

[Michael Soskind]

Hi Blake,

Using a for loop, your code could look as follows:

for i = 1:magic_number              % iterate for the number of items in resulting_array
    % add a random number up to magic number, and add n-1*randi
    resulting_array(i) = randi(magic_number) + (i-1)*randi(magic_number);
end

This should yield what you are looking for, and hope that helps

Michael

[Blake Seaton]

Hi Michael, your code was just a bit off (want the added interval to be the same each time, not random), but it got me to the correct answer:

for i = 1:magic_number
    resulting_array(i) = randi(magic_number) + (i-1)*(magic_number);
end

Thank you!