# tally(VisibleList) -- tally the elements of a list, sequence, or array

## Synopsis

• Function: tally
• Usage:
y = tally x
• Inputs:
• x, ,
• Outputs:
• y, , a listing of tallied results

## Description

It produces an hash table (multiset) y which tallies the frequencies of occurrences of items in the list x, i.e., y_i is the number of times i appears in x, or is 0 if i doesn't appear in the list.
 i1 : y = tally {1,2,3,a,b,1,2,a,1,2,{a,b},{a,b},a} o1 = Tally{{a, b} => 2} 1 => 3 2 => 3 3 => 1 a => 3 b => 1 o1 : Tally i2 : y_2 o2 = 3 i3 : y_5 o3 = 0 i4 : y_{a,b} o4 = 2