Pairs of similar vectors (or objects) in a set of vectors (or objects) are identified. A comparison vector x in a set of vectors is identified; a size threshold is determined such that if a similarity between the vector x and a vector y in the set of vectors is equal to or greater than a similarity threshold, then the vector y has a size at least equal to the size threshold, the size of the candidate vector y being determined based on a number of non-zero features in the vector y. A vector having a size less than the size threshold is removed from the set of candidate vectors.