fdasrvf (version 2.2.0)

curve_srvf_align: Align Curves

Description

Aligns a collection of curves using the elastic square-root velocity (srvf) framework. If the curves are describing multidimensional functional data, then rotated == FALSE and mode == 'O'

Usage

curve_srvf_align(
  beta,
  mode = "O",
  rotated = TRUE,
  scale = FALSE,
  lambda = 0,
  maxit = 20,
  ms = "mean"
)

Value

Returns a list containing

betan

aligned curves

qn

aligned srvfs

betamean

mean curve

q_mu

mean SRVFs

Arguments

beta

Array of sizes \(n \times T \times N\) for \(N\) curves of dimension \(n\) evaluated on a grid of \(T\) points

mode

Open ("O") or Closed ("C") curves

rotated

Optimize over rotation (default = TRUE)

scale

Include scale (default = FALSE)

lambda

A numeric value specifying the elasticity. Defaults to 0.0.

maxit

maximum number of iterations

ms

string defining whether the Karcher mean ("mean") or Karcher median ("median") is returned (default = "mean")

References

Srivastava, A., Klassen, E., Joshi, S., Jermyn, I., (2011). Shape analysis of elastic curves in euclidean spaces. Pattern Analysis and Machine Intelligence, IEEE Transactions on 33 (7), 1415-1428.

Examples

data("mpeg7")
# note: use more shapes and iterations, small for speed
out = curve_srvf_align(beta[,,1,1:2],maxit=2)