landmarks_regradi {pliman}

Pseudolandmarks with equally spaced angles

Description

Select n landmarks that are spaced with a regular sequence of angles taken between the outline coordinates and the centroid.

Usage

landmarks_regradi(
  x,
  n = 50,
  close = TRUE,
  plot = TRUE,
  ncol = NULL,
  nrow = NULL
)

Arguments

x

A matrix, a data.frame a list of perimeter coordinates, often produced with object_contour().

n

Number of points to be sampled. Defaults to 50.

close

Return a closed polygon? Defaults to TRUE.

plot

Create a plot? Defaults to TRUE.

ncol, nrow

The number of rows or columns in the plot grid when a list is used in x. Defaults to NULL, i.e., a square grid is produced.

Value

A list with the following objects:

• pixindices: Vector of radius indices.

• radii: Vector of sampled radii lengths.

• Xc: The centroid coordinate of x axis.

• Yc: The centroid coordinate of y axis.

• coords: Coordinates of sampled points arranged in a two-column matrix.

If x is a list, a list of objects described above is returned.

Note

Borrowed from Claude (2008), pp. 53

References

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

Examples

library(pliman)
plot_polygon(contours[[1]])
ldm <- landmarks_regradi(contours)