Tally - Tally -- difference of tallies

Tally - Tally -- difference of tallies

Synopsis:

Operator: - -- a unary or binary operator, usually used for negation or subtraction

Input:

an instance of class Tally.

Output:

an instance of class Tally.

x - y -- produces the difference of two tallies.

i1 : tally {a,a,b,c} - tally {c,d,d}



o1 = Tally{a => 2 }

           b => 1

           d => -2



o1 : Tally

See also:

Tally -- the class of all tally results

Code:

     -- ../../../Macaulay2/m2/set.m2:27
     Tally - Tally := Tally => (x,y) -> select(merge(x,applyValues(y,minus),plus),i -> i =!= 0)