How to implement a set in MATLAB?

In the algorithm below, you can see that there is a variable, C, initialized to the empty set. How would I go about creating a set in MATLAB? Because of this confusion I am unclear on how to code lines 5 and 7 of the algorithm. Furthermore, I am unclear of how to implement the condition on line 13. What is the best way to implement this logic?

Answer 1

[Jonathan Mayers]

Thank you for the responses. I have arrived at what I needed and hope it will help anyone in the future viewing this post.

First, each Ci is a different set so C can be a (mx*my+1)-by-N matrix of zeros where each row would a different set Ci.

 C = zeros(mx*my+1,N);

Next, the logic of lines 5 and 7 can be coded as below where col_t and col_f are the indices of the column to change when the condition is true or false respectively. They are initialized to 1 before the for loop.

 %%line 5
 row = (i-1)*mx+j;
 C(row,col_t) = n;
 col_t = col_t + 1;

 %%line 7
 row = mx*my+1;
 C(row,col_f) = n;
 col_f = col_f + 1;

Finally, after line 11 and before the for loop of line 12, you can extract the subset with the following code:

 Ci = C(i,:);

And the condition on line 13 would be as Titus answered:

 if ismember(n,Ci)

Answer 2

[Walter Roberson]

If you want an actual set, in the sense of an unordered collection in which there can be at most one "copy" of any given value, then you can use a vector together with the union and setdiff operators.

Answer 3

[Titus Edelhofer]

Hi,

if I see it correctly, your "set" is meant to be a set of numbers? In this case you might simply use a vector in MATLAB. And the empty set in this case would be

C = [];

To test if an element of a "set", use the function ismember, so line 13 would read

if ismember(n, C)

Titus Titus

[Jonathan Mayers]

Thank you. So for example, I can code the assignment in line 5 as below?

 index = (i-1)*mx+j;
 C(index) = n;