MATLAB Language Set operations Elementary set operations
Example
It's possible to perform elementary set operations with Matlab. Let's assume we have given two vectors or arrays
A = randi([0 10],1,5);
B = randi([-1 9], 1,5);
and we want to find all elements which are in A and in B. For this we can use
C = intersect(A,B);
C will include all numbers which are part of A and part of B.
If we also want to find the position of these elements we call
[C,pos] = intersect(A,B);
pos is the position of these elements such that C == A(pos).
Another basic operation is the union of two sets
D = union(A,B);
Herby contains D all elements of A and B.
Note that A and B are hereby treated as sets which means that it does not matter how often an element is part of A or B. To clarify this one can check
D == union(D,C).
If we want to obtain the data that is in 'A' but not in 'B' we can use the following function
E = setdiff(A,B);
We want to note again that this are sets such that following statement holds D == union(E,B).
Suppose we want to check if
x = randi([-10 10],1,1);
is an element of either A or B we can execute the command
a = ismember(A,x);
b = ismember(B,x);
If a==1 then x is element of A and x is no element is a==0. The same goes for B. If a==1 && b==1 x is also an element of C. If a == 1 || b == 1 x is element of D and if a == 1 || b == 0 it's also element of E.
