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Don't you mean a python set? But yes, for use cases containing many duplicates where the result easily fits in memory, that is probably the fastest.



Fun fact: they are nearly the same implementation. See: http://markmail.org/message/ktzomp4uwrmnzao6


As one would generally expect, the backing store of most hashsets is little more than a hashmap with zero-sized/no values.

In fact, that's exactly how Rust's standard library hashset is implemented since rust supports zero-sized types "in userland" (and unit `()` is a ZST):

    pub struct HashSet<T, S = RandomState> {
        map: HashMap<T, (), S>
    }
http://doc.rust-lang.org/src/std/collections/hash/set.rs.htm...


a set replaces 'sort -u' or 'sort | uniq'. A dictionary replaces 'sort | uniq -c'




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