Type: Package
Title: Generate Open or Closed Interpolating Curves
Version: 0.2.0
Author: Bill Venables
Maintainer: Bill Venables <Bill.Venables@gmail.com>
Description: Functions for finding smooth interpolating curves connecting a series of points in the plane. Curves may be open or closed, that is, with the first and last point of the curve at the initial point.
License: GPL-2
Imports: stats, sp
Depends: graphics, grDevices
Encoding: UTF-8
RoxygenNote: 7.2.0
Suggests: ggplot2, knitr, rmarkdown
VignetteBuilder: knitr
NeedsCompilation: no
Packaged: 2022-06-18 00:18:47 UTC; bill
Repository: CRAN
Date/Publication: 2022-06-18 06:30:06 UTC

Check if points lie inside a simple polygon

Description

Check if points lie inside a simple polygon

Usage

points %inside% polygon

Arguments

points

a data.frame with components x,y specifying the points

polygon

a data.frame with components x,y specifying the polygon

Value

a logical value matching the number of points, TRUE = "inside"

Examples

oldPar <- par(pty = "s", las = 1, xpd = NA)
pts <- expand.grid(x = seq(0, 1, len=25), y = seq(0, 1, len=25))
pol <- (1 + 1i)/2 + complex(argument = seq(-base::pi, base::pi, len=100))/3
show_red <- as_points(pts) %inside% as_polygon(pol)
plot(pts, col = ifelse(show_red, "red", "royal blue"), ann = FALSE, bty = "n",
     pch = ".", cex = ifelse(show_red, 4, 2.5), asp = 1)
polygon(pol, lwd = 0.5)
par(oldPar)

Interactive curve adjustment

Description

A simple interactive device for adjusting a curve. Given a set of points, the curve is plotted and may then be adjusted interactively by clicking on any of the points, one at a time, and clicking again at its intended new position.

Usage

adjust_curve(
  x,
  y = NULL,
  ...,
  plotit = TRUE,
  curve = open_curve,
  ccolour = "#DF536B",
  pcolour = "#2297E6"
)

Arguments

x, y

Any means of specifying points in the plane, as accepted by xy.coords()

...

additional arguments past on to curve()

plotit

logical: should the curve be plotted (TRUE) or can it be assumed the points are already on the display (FALSE)?

curve

One of the curve type functions of this package

ccolour

character string: colour for the curve in the plot

pcolour

character string: colour for the points in the plot

Value

The adjusted points which define the adjusted curve

Conversion to data frame

Description

Method function to convert an object inheriting from class "curve" to a data.frame

Usage

## S3 method for class 'curve'
as.data.frame(x, row.names = NULL, optional = FALSE, ...)

Arguments

x

An object inheriting from class "curve"

row.names, optional, ...

as for as.data.frame.

Value

A data frame object

Examples

library(ggplot2)
set.seed(1234)
z <- complex(real = runif(5), imaginary = runif(5))
z <- z[order(Arg(z - mean(z)))]
cz <- closed_curve(z)
oz <- open_curve(z)
ggplot() + geom_path(data = as.data.frame(cz), aes(x,y), colour = "#DF536B") +
    geom_path(data = as.data.frame(oz), aes(x,y), colour = "#2297E6") +
    geom_point(data = as.data.frame(z), aes(x = Re(z), y = Im(z))) +
    geom_segment(data = as.data.frame(z), aes(x = Re(mean(z)),
                                              y = Im(mean(z)),
                                              xend = Re(z),
                                              yend = Im(z)),
                 arrow = arrow(angle=15, length=unit(0.125, "inches")),
                 colour = alpha("grey", 1/2)) +
    theme_bw()

Coerce two dimensional points to complex

Description

Convenience function for allowing any of the usual ways two dimensional points can be specified in traditional graphics to define a complex variable

Usage

as_complex(x, y = NULL)

Arguments

x, y

A two dimensional specification, as allowed by grDevices::xy.coords

Value

A complex vector

Examples

loc <- cbind(runif(20), runif(20))
z <- as_complex(loc)
z <- z-mean(z)
Mod(z) <- 1
z <- z[order(Arg(z))]
plot(closed_curve(z), asp = 1, col = 2)
lines(z, col = 4)
points(z, pch=16)

Make a Simple Polygon or Points

Description

A simple polygon is here defined as a data frame with numeric components x and y without any duplicate rows. The order of rows is significant in defining the associated figure.

Usage

as_polygon(x, y = NULL, ...)

## Default S3 method:
as_polygon(x, y = NULL, ...)

## S3 method for class 'curve'
as_polygon(x, y = NULL, ...)

as_points(x, y = NULL)

Arguments

x, y

any specification of 2-d points, or a "curve" object

...

additional arguments not currently used

Details

A 'points' object is defined as a data frame with numeric columns x and y.

Value

a data frame with components x and y

Complex vector property replacement functions

Description

Complex vector property replacement functions

Usage

Re(x) <- value

Im(x) <- value

Mod(x) <- value

Arg(x) <- value

Arguments

x

a complex vector to be altered

value

the numerical value vector to be used in the alteration

Value

An appropriately modified complex vector

Curved Interpolation

Description

Interpolate between ordered 2-d points with a smooth curve. open_curve() produces an open curve; closed_curve() produces a closed curve. Bezier curves are also provided.

Usage

open_curve(x, y = NULL, n = 100 * length(z), asp = 1, ...)

## S3 method for class 'curve'
plot(
  x,
  y = NULL,
  type = "l",
  lty = "solid",
  xpd = NA,
  pch = 20,
  ...,
  include_points = TRUE
)

## S3 method for class 'curve'
points(x, pch = 20, xpd = NA, ...)

## S3 method for class 'curve'
lines(x, xpd = NA, ...)

closed_curve(x, y = NULL, n0 = 500 * length(z0), asp = 1, ...)

bezier_curve(x, y = NULL, n = 500, t = seq(0, 1, length.out = n), ...)

Arguments

x, y

Any of the forms used to specify a 2-d set of points or an object of class "curve"

n, n0

number of points in the interpolating curve

asp

the relative scale for x versus that of y

...

additional arguments past on to other methods

pch, type, lty, xpd

plot arguments or traditional graphics parameters

include_points

logical:should points be included in the plot?

t

for Bezier curves, parameter value sequence ranging from 0 to 1

Value

a list with components x, y, and points, of S3 class "curve"

Examples

oldPar <- par(pty = "s", mfrow = c(2, 2), mar = c(1,1,2,1), xpd = NA)
z <- (complex(argument = seq(-0.9*base::pi, 0.9*base::pi, length = 20)) +
     complex(modulus = 0.125, argument = runif(20, -base::pi, base::pi))) *
     complex(argument = runif(1, -base::pi, base::pi))

plot(z, asp=1, axes = FALSE, ann = FALSE, panel.first = grid())
title(main = "Open")
segments(Re(z[1]), Im(z[1]), Re(z[20]), Im(z[20]), col = "grey", lty = "dashed")
lines(open_curve(z), col = "red")

plot(z, asp=1, axes = FALSE, ann = FALSE, panel.first = grid())
title(main = "Closed")
lines(closed_curve(z), col = "royal blue")

plot(z, asp=1, axes = FALSE, ann = FALSE, panel.first = grid())
title(main = "Bezier")
lines(bezier_curve(z), col = "dark green")

plot(z, asp=1, axes = FALSE, ann = FALSE, panel.first = grid())
title(main = "Circle")
lines(complex(argument = seq(-base::pi, base::pi, len = 500)),
      col = "purple")

par(oldPar)