Set routines

Making proper sets

unique(ar[, return_index, return_inverse, ...])	Find the unique elements of an array.
in1d(ar1, ar2[, assume_unique, invert, kind])	Test whether each element of this 1-D array is also present in a second array.
isin(element, test_elements[, ...])	Calculates element in test_elements, broadcasting over element only.