Radii variation Fourier transform

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Description

rfourier computes radii variation Fourier analysis from a matrix or a list of coordinates.

Usage

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rfourier(x, ...)

## Default S3 method:
rfourier(x, nb.h, smooth.it = 0, norm = FALSE,
  verbose = TRUE, ...)

## S3 method for class 'Out'
rfourier(x, nb.h = 40, smooth.it = 0, norm = TRUE,
  verbose = TRUE, ...)

Arguments

x

A list or matrix of coordinates or an Out object

...

useless here

nb.h

integer. The number of harmonics to use. If missing 99pc harmonic power is used.

smooth.it

integer. The number of smoothing iterations to perform.

norm

logical. Whether to scale the outlines so that the mean length of the radii used equals 1.

verbose

logical. Whether to display diagnosis messages.

Details

see the JSS paper for the maths behind.

Value

A list with following components:

  • an vector of a_{1->n} harmonic coefficients

  • bn vector of b_{1->n} harmonic coefficients

  • ao ao harmonic coefficient.

  • r vector of radii lengths.

Note

Directly borrowed for Claude (2008), and called fourier1 there.

References

Claude, J. (2008) Morphometrics with R, Use R! series, Springer 316 pp.

See Also

Other rfourier: rfourier_i, rfourier_shape

Examples

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data(bot)
coo <- coo_center(bot[1]) # centering is almost mandatory for rfourier family
coo_plot(coo)
rf  <- rfourier(coo, 12)
rf
rfi <- rfourier_i(rf)
coo_draw(rfi, border='red', col=NA)

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