efourier_i {Momocs}

Inverse elliptical Fourier transform

Description

efourier_i uses the inverse elliptical Fourier transformation to calculate a shape, when given a list with Fourier coefficients, typically obtained computed with efourier.

Usage

efourier_i(ef, nb.h, nb.pts = 120)

Arguments

ef

list. A list containing a_n, b_n, c_n and d_n Fourier coefficients, such as returned by efourier.

nb.h

integer. The number of harmonics to use. If not specified, length(ef$an) is used.

nb.pts

integer. The number of points to calculate.

Details

See efourier for the mathematical background.

Value

A matrix of (x; y) coordinates.

Note

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

References

Claude, J. (2008) Morphometrics with R, Use R! series, Springer 316 pp. Ferson S, Rohlf FJ, Koehn RK. 1985. Measuring shape variation of two-dimensional outlines. Systematic Biology 34: 59-68.

See Also

Other efourier: efourier_shape(), efourier()

Examples

coo <- bot[1]
coo_plot(coo)
ef  <- efourier(coo, 12)
ef
efi <- efourier_i(ef)
coo_draw(efi, border='red', col=NA)