level1_unit_orientation: Level-1 unit in the Peano curve and Meander curve

In sfcurve: 2x2, 3x3 and Nxn Space-Filling Curves

Level-1 unit in the Peano curve and Meander curve

Description

Level-1 unit in the Peano curve and Meander curve

Usage

## S4 method for signature 'sfc_3x3_peano'
level1_unit_orientation(p)

## S4 method for signature 'sfc_3x3_peano'
change_level1_unit_orientation(p, to = c("horizontal", "vertical"))

## S4 method for signature 'sfc_3x3_meander'
level1_unit_orientation(p)

## S4 method for signature 'sfc_3x3_meander'
change_level1_unit_orientation(p, to = c("forward", "backward"))

Arguments

p	For 'level1_unit_orientation()', it is an 'sfc_3x3_peano' or 'sfc_3x3_meander' unit on level 1. For 'change_level1_unit_orientation()', it is a normal 'sfc_3x3_peano' or 'sfc_3x3_meander' object.
to	A string of "vertical/horizontal" (on the 'sfc_3x3_peano' object) or "forward/backward" (on the 'sfc_3x3_meander' object).

Details

"vertical" and "horizontal" correspond to the direction of the "long segments" in a Peano curve (see **Examples**).

'level1_unit_orientation()' is normally used inside ['sfc_apply()']. 'change_level1_unit_orientation()' changes all level-1 units of a Peano curve or a Meander curve simultaneously.

Value

'level1_unit_orientation()' returns "verticalhorizontal" (on the 'sfc_3x3_peano' object) or "forward/backward" (on the 'sfc_3x3_meander' object).

'change_level1_unit_orientation()' returns an 'sfc_3x3_peano' or 'sfc_3x3_meander' object.

Examples

p = sfc_3x3_peano("I", 111)
# the first level-1 unit
level1_unit_orientation(p[1:9, TRUE])
# the fourth level-1 unit
level1_unit_orientation(p[1:9 + 27, TRUE])
p2 = change_level1_unit_orientation(p, "horizontal")
p3 = change_level1_unit_orientation(p, "vertical")
draw_multiple_curves(p, p2, p3, 
    title = c("original", "all horizontal", "all vertical"), nrow = 1)
# by default, orientations of all level-1 units in Meander curve are forward
p = sfc_3x3_meander("I", 111)
level1_unit_orientation(p[1:9, TRUE])
p2 = change_level1_unit_orientation(p, "backward")
draw_multiple_curves(p, p2,
   title = c("all forward", "all backward"), nrow = 1)

sfcurve documentation built on April 10, 2026, 5:06 p.m.