trends ( seq -- slices )
Splitting trending sequences

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upward-slices ( seq -- slices )

Vocabulary
splitting.monotonic

Inputs

seq	a sequence

Outputs

slices

a sequence of downward, stable, and upward slices

Word description
Returns a sorted sequence of downward, stable, or upward slices. The endpoints of some slices may overlap with each other.

Examples

USING: splitting.monotonic math prettyprint ; { 1 2 3 3 2 1 } trends .
{ T{ upward-slice { to 3 } { seq { 1 2 3 3 2 1 } } } T{ stable-slice { from 2 } { to 4 } { seq { 1 2 3 3 2 1 } } } T{ downward-slice { from 3 } { to 6 } { seq { 1 2 3 3 2 1 } } } }

Definition

USING: accessors kernel math sequences sorting ;

IN: splitting.monotonic

: trends ( seq -- slices )
    dup length dup 1 > [
        drop
        [ downward-slices ] [ stable-slices ] [ upward-slices ]
        tri 3append [ from>> ] sort-by
    ] [ zero? [ drop { } ] [ [ 0 1 ] dip stable-slice boa ] if ]
    if ;