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Sets

Sets represent unordered collections of unique elements. They are useful for deduplication, membership tests, and set operations (union, intersection, difference).

s = {1, 2, 3}
s.add(4)
s.discard(2)
print(3 in s)  # membership

# Set operations
a = {1,2,3}
b = {3,4,5}
print(a & b)  # intersection
print(a | b)  # union
print(a - b)  # difference

% Unique and set operations
A = [1 2 3 2];
U = unique(A);        % [1 2 3]
B = [3 4 5];
inter = intersect(U, B);
uni = union(U, B);
diff = setdiff(U, B);

Gotchas

  • Sets are unordered; you cannot rely on iteration order.
  • Elements must be hashable/eligible for set membership (immutable) in Python.
  • Matlab set functions work on arrays and return sorted unique results.