rfourier_i {Momocs}

Inverse radii variation Fourier transform

Description

rfourier_i uses the inverse radii variation (equally spaced radii) transformation to calculate a shape, when given a list with Fourier coefficients, typically obtained computed with rfourier.

Usage

rfourier_i(rf, nb.h, nb.pts = 120)

Arguments

rf

A list with ao, an and bn components, typically as returned by rfourier.

nb.h

integer. The number of harmonics to calculate/use.

nb.pts

integer. The number of points to calculate.

Details

See the JSS paper for the maths behind.

Value

A list with components:

x

vector of x-coordinates.

y

vector of y-coordinates.

angle

vector of angles used.

r

vector of radii calculated.

Note

Directly borrowed for Claude (2008), and called ifourier1 there.

References

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

See Also

Other rfourier: rfourier_shape(), rfourier()

Examples

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)