1. A method of identifying an unknown vapor as either belonging to a class or not, wherein the class comprises known vapors of interest, said method comprising the steps of: introducing a sample of an unknown vapor into at least one sensor coated with a vapor-sensitive coating, generating a weight vector corresponding to a N-space representation of the class; generating a N-space representation of the unknown vapor and generating an unknown pattern vector based thereon; and calculating the dot product of said unknown pattern vector and the weight vector to determine whether the unknown vapor is within said class, wherein the dot product producing a positive number is a member of the class in question while a negative number is not.