sfc_apply: Apply to every unit in the sfc_nxn curve

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

Apply to every unit in the sfc_nxn curve

Description

Apply to every unit in the sfc_nxn curve

Usage

## S4 method for signature 'sfc_nxn'
sfc_apply(p, depth = 1, fun = function(x) x)

Arguments

p	An sfc_nxn object.
depth	An integer between 0 and level-1 of the curve.
fun	A function of which the argument x is a subunit in the curve. The subunit is an sfc_nxn object but only contains the current sub-sequence. The function should return an sfc_seuqence object with the same length as of x. The function can take an optional second argument which the index of the current subunit in the curve.

Details

This function is mainly used to flip subunits on various levels on the curve, thus mainly on the Peano curve and the Meander curve. A depth of 0 corresponds to the complete curve. A depth of 1 corresponds to the nine first-level units, et al.

Currently, sfc_apply() only works on curves with a single base pattern as the seed.

Value

An sfc_nxn object.

Examples

p = sfc_3x3_peano("I", level = 3)
# flip the global curve
draw_multiple_curves(
    p, 
    sfc_apply(p, 0, sfc_flip_unit),
    nrow = 1
)

# flip all the subunits on depth = 1
draw_multiple_curves(
    p, 
    sfc_apply(p, 1, sfc_flip_unit),
    nrow = 1
)

# flip all the subunits on depth = 2
draw_multiple_curves(
    p, 
    sfc_apply(p, 2, sfc_flip_unit),
    nrow = 1
)

# flip all level-1 patterns on the Peano curve to horizontal
# only works on the lowest subunit, 
p2 = sfc_apply(p, 2, function(x) {
    if(level1_unit_orientation(x) == "vertical") {
        sfc_flip_unit(x)
    } else {
        x
    }
})
# then on depth=1, only flip the unit with odd index
p3 = sfc_apply(p2, 1, function(x, i) {
    if(i %% 2 == 1) {
        sfc_flip_unit(x)
    } else {
        x
    }
})
draw_multiple_curves(p2, p3, nrow = 1)

# flip all level-1 patterns to vertical
p3 = sfc_apply(p, 2, function(x) {
    if(level1_unit_orientation(x) == "horizontal") {
        sfc_flip_unit(x)
    } else {
        x
    }
})
draw_multiple_curves(p, p3, nrow = 1)

sfcurve documentation built on Sept. 14, 2024, 1:07 a.m.