Momocs (version 0.2-03)

efourier.i: Calculates inverse elliptical Fourier analysis.

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 = 300)

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.

Value

• A list with components:
• x
  vector of x-coordinates.
• y
  vector of y-coordinates.

Details

See efourier for the mathematical background.

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

efourier for the reverse operation. l2m, coeff.split may be useful.

Examples

data(bot)
coo <- bot@coo[[1]]
coo.plot(coo)
ef  <- efourier(coo, 12)
ef
efi <- efourier.i(ef)
l2m(efi)
coo.draw(efi, border="red", col=NA)