Vocabulary
math.statistics

Inputs and outputs

seq	a sequence
hashtable	a hashtable

Word description
Returns a hashtable where the keys are the elements of the sequence and the values are the number of times they appeared in that sequence.

Examples

! Count the number of times an element appears in a sequence. USING: prettyprint math.statistics ; "aaabc" histogram .
H{ { 97 3 } { 98 1 } { 99 1 } }

Definition

IN: math.statistics

: histogram ( seq -- hashtable ) [ ] histogram-by ;