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fdasrvf (version 2.0.0)

f_to_srvf: Transformation to SRSF Space

Description

This function transforms curves from their original functional space to the SRVF space.

Usage

f_to_srvf(f, time, multidimensional = FALSE)

Value

A numeric array of the same shape as the input array f storing the SRSFs of the original curves.

Arguments

f

Either a numeric vector of a numeric matrix or a numeric array specifying the functions that need to be transformed.

  • If a vector, it must be of shape \(M\) and it is interpreted as a single \(1\)-dimensional curve observed on a grid of size \(M\).

  • If a matrix and multidimensional == FALSE, it must be of shape \(M \times N\). In this case, it is interpreted as a sample of \(N\) curves observed on a grid of size \(M\), unless \(M = 1\) in which case it is interpreted as a single \(1\)-dimensional curve observed on a grid of size \(M\).

  • If a matrix and multidimensional == TRUE,it must be of shape \(L \times M\) and it is interpreted as a single \(L\)-dimensional curve observed on a grid of size \(M\).

  • If a 3D array, it must be of shape \(L \times M \times N\) and it is interpreted as a sample of \(N\) \(L\)-dimensional curves observed on a grid of size \(M\).

time

A numeric vector of length \(M\) specifying the grid on which the curves are evaluated.

multidimensional

A boolean specifying if the curves are multi-dimensional. This is useful when f is provided as a matrix to determine whether it is a single multi-dimensional curve or a collection of uni-dimensional curves. Defaults to FALSE.

References

Srivastava, A., Wu, W., Kurtek, S., Klassen, E., Marron, J. S., May 2011. Registration of functional data using Fisher-Rao metric, arXiv:1103.3817v2.

Tucker, J. D., Wu, W., Srivastava, A., Generative models for functional data using phase and amplitude Separation, Computational Statistics and Data Analysis (2012), 10.1016/j.csda.2012.12.001.

Examples

Run this code
q <- f_to_srvf(simu_data$f, simu_data$time)

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