readland.nts: Read landmark data matrix from nts file

Description

Read *.nts file to obtain landmark coordinates for a set of specimens

Usage

readland.nts(file)

Arguments

file

A *.nts file containing two- or three-dimensional landmark data

Value

Function returns a (p x k x n) array, where p is the number of landmark points, k is the number of landmark dimensions (2 or 3), and n is the number of specimens. The third dimension of this array contains names for each specimen, which are obtained from the image names in the *.nts file.

Details

Function reads a *.nts file containing a matrix of two- or three-dimensional landmark coordinates. NTS files are text files in one of the standard formats for geometric morphometrics (see Rohlf 2012). The parameter line contains 5 or 6 elements, and must begin with a "1" to designate a rectangular matrix. The second and third values designate how many specimens (n) and how many total variables (p x k) are in the data matrix. The fourth value is a "0" if the data matrix is complete and a "1" if there are missing values. If missing values are present, the '1' is followed by the arbitrary numeric code used to represent missing values (e.g., -999). These values will be replaced with "NA" in the output array. Subsequent analyses requires a full complement of data, see estimate.missing. The final value of the parameter line denotes the dimensionality of the landmarks (2,3) and begins with "DIM=". If specimen and variable labels are included, these are designated placing an "L" immediately following the specimen or variable values in the parameter file. The labels then precede the data matrix. Function is for *.nts file containing landmark coordinates for multiple specimens. Note that *.dta files in the nts format written by Landmark Editor http://graphics.idav.ucdavis.edu/research/projects/EvoMorph, and *.nts files written by Stratovan Checkpoint http://www.stratovan.com/ have incorrect header notation; every header is 1 n p-x-k 1 9999 Dim=3, rather than 1 n p-x-k 0 Dim=3, which denotes that missing data is in the file even when it is not.

References

Rohlf, F. J. 2012 NTSYSpc: Numerical taxonomy and multivariate analysis system. Version 2.2. Exeter Software, New York.