An Erlang library inspired by Python's collections.Counter
$ rebar3 compile> A = #{a => 2}.
#{a => 2}
> B = #{b => 5, d => 4}.
#{b => 5,d => 4}
> C = counter:count([a,b,c,b,b,a]).
#{a => 2,b => 3,c => 1}
> counter:count_with(fun(E) -> {E,5} end, [a,b,c]).
#{a => 5,b => 5,c => 5}
> counter:from_list([{a,1}, {a,1}, {b,1}, {b,2}, {c,1}]).
#{a => 2,b => 3,c => 1}
> counter:incr(C, a).
#{a => 3,b => 3,c => 1}
> counter:incr(C, a, 10).
#{a => 12,b => 3,c => 1}
> counter:add(C, C).
#{a => 4,b => 6,c => 2}
> counter:subtract(A,B).
#{a => 2,b => -5,d => -4}
> counter:dups(C).
#{a => 2,b => 3}
> counter:unique(C).
[c]
> counter:max(C).
{b,3}
> counter:most_common(C, 2).
[{b,3},{a,2}]
> counter:least_common(C, 2).
[{c,1},{a,2}]
> counter:min(C).
{c,1}
> counter:elements(C).
[a,a,b,b,b,c]
> counter:union(B, C).
#{a => 2,b => 5,c => 1,d => 4}
> counter:intersection(B, C).
#{b => 3}
> counter:only_positive(#{a => 5, b => -5, c => 0}).
#{a => 5}
> counter:sum(C).
6