Momocs (version 1.1.6)

sfourier: 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)
# S3 method for default
sfourier(x, nb.h)
# S3 method for Out
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

References

Renaud S, Pale JRM, 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("E") %>%
   coo_sample(360) %T>% coo_plot(zoom=2) %>% sfourier(16) %>%
   sfourier_i() %>% coo_draw(bor="red", points=TRUE)