
rfourier_shape
calculates a 'Fourier radii variation shape' given
Fourier coefficients (see Details
) or can generate some 'rfourier'
shapes.
rfourier_shape(an, bn, nb.h, nb.pts = 80, alpha = 2, plot = TRUE)
A matrix of (x; y) coordinates.
numeric
. The
numeric
. The
integer
. The number of harmonics to use.
integer
. The number of points to calculate.
numeric
. The power coefficient associated with the
(usually decreasing) amplitude of the Fourier coefficients (see
Details).
logical
. Whether to plot or not the shape.
rfourier_shape
can be used by specifying nb.h
and
alpha
. The coefficients are then sampled in an uniform distribution
alpha
is lower than 1, consecutive
coefficients will thus increase. See rfourier for the mathematical
background.
Claude, J. (2008) Morphometrics with R, Use R! series, Springer 316 pp.
Other rfourier:
rfourier_i()
,
rfourier()
data(bot)
rf <- rfourier(bot[1], 24)
rfourier_shape(rf$an, rf$bn) # equivalent to rfourier_i(rf)
rfourier_shape() # not very interesting
rfourier_shape(nb.h=12) # better
rfourier_shape(nb.h=6, alpha=0.4, nb.pts=500)
# Butterflies of the vignette' cover
panel(Out(a2l(replicate(100,
rfourier_shape(nb.h=6, alpha=0.4, nb.pts=200, plot=FALSE)))))
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