Creates a subset of a pedigree by retaining the ancestors of a specified subset of individuals
prunePed(pedigree, keep, make.base=FALSE)
subsetted pedigree
pedigree with id in column 1 dam in column 2 and sire in column 3
individuals in pedigree for which the ancestors should be retained
logical: should ancestors that do not provide additional information be discarded?
Jarrod Hadfield j.hadfield@ed.ac.uk + Michael Morrissey