straightenedBezier: Straightened Spline curves
In AEBilgrau/Bmisc: Biostatistical miscellaneous functions

Description Usage Arguments Value Note Author(s) References Examples

Function for straightning Bezier or B-spline curves.

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straightenedBezier(x, y, beta = 0.5, n.evals = 100)

straightenedBSpline(x, y, order = 4, beta = 0.5, n.evals = 100)

`x`	A numeric vector giving the x-coordinates of the control points. Alternatively, it can be a `list` (or `data.frame`) containing two vectors of control points.
`y`	A numeric vector giving the y-coordinates of the control points.
`beta`	A numeric values that control amount of straightening. A `beta` of 1 is a normal spline curve and where as a value of 0 is a straight line.
`n.evals`	The number of evaluations of the Bezier curve.
`order`	The order of the B-spline. See `bSpline`.

Returns a list of length 2 with entries x and y of x and y coordinates corresponding to the evaluations of the B-spline.

The straightening is done by modifying the control points as described in the reference.

Anders Ellern Bilgrau

Holten, Danny. "Hierarchical edge bundles: Visualization of adjacency relations in hierarchical data." Visualization and Computer Graphics, IEEE Transactions on 12.5 (2006): 741-748.

# Bezier curves
x <- list(x = cumsum(rnorm(7)), 
          y = cumsum(rnorm(7)))
plot(x, type = "b", col = "grey", pch = 16)
for (b in seq(0.1, 1, l = 9)) 
  lines(Bmisc:::straightenedBezier(x, beta = b))
# B-splines
x <- cumsum(rnorm(7))
y <- cumsum(rnorm(7))
plot(x, y, type = "b", col = "grey", pch = 16)
for (b in seq(0.1, 0.9, l = 9)) 
  lines(Bmisc:::straightenedBSpline(x, y, beta = b))