group-by ( seq quot: ( elt -- key ) -- groups )

Vocabulary

grouping.extras

Inputs

seq	a sequence
quot	a quotation with stack effect ( elt -- key )

Outputs

groups

a new assoc

Word description

Groups consecutive elements by the key received by applying quot to each element in the sequence.

Examples

USING: grouping.extras unicode.data prettyprint sequences strings ; "THis String Has CasE!" [ category ] group-by [ last >string ] { } map-as .
{ "TH" "is" " " "S" "tring" " " "H" "as" " " "C" "as" "E" "!" }

USING: grouping.extras prettyprint sequences strings ; { "apple" "anchovy" "banana" "anise" "bagel" "bratwurst" } [ first 1string ] group-by .
V{ { "a" V{ "apple" "anchovy" } } { "b" V{ "banana" } } { "a" V{ "anise" } } { "b" V{ "bagel" "bratwurst" } } }

See also

collect-by

Definition

USING: combinators grouping.extras.private kernel sequences ;

IN: grouping.extras

: group-by ( seq quot: ( elt -- key ) -- groups )
    [ [ dup ] ] dip [ ( x -- y ) call-effect (group-by) ] curry
    compose V{ } clone swap reduce ;