sfourier {Momocs}

Radii variation Fourier transform (equally spaced curvilinear abscissa)

Description

sfourier computes radii variation Fourier analysis from a matrix or a list of coordinates where points are equally spaced aong the curvilinear abscissa.

Usage

sfourier(x, nb.h)

## Default S3 method:
sfourier(x, nb.h)

## S3 method for class 'Out'
sfourier(x, nb.h)

## S3 method for class 'list'
sfourier(x, nb.h)

Arguments

x

A list or matrix of coordinates or an Out object

nb.h

integer. The number of harmonics to use. If missing, 12 is used on shapes; 99 percent of harmonic power on Out objects, both with messages.

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

The implementation is still quite experimental (as of Dec. 2016)

References

Renaud S, Michaux JR (2003): Adaptive latitudinal trends in the mandible shape of Apodemus wood mice. J Biogeogr 30:1617-1628.

See Also

Other sfourier: sfourier_i(), sfourier_shape()

Examples

molars[4] %>%
coo_center %>% coo_scale %>% coo_interpolate(1080) %>%
coo_slidedirection("right") %>%
   coo_sample(360) %T>% coo_plot(zoom=2) %>%
   sfourier(16) %>%
   sfourier_i() %>%
   coo_draw(bor="red", points=TRUE)