Estimates nucleotide diversity \(\pi= \sum_l 2 p_ l(1-p_l) 2n/(2n-1)\) from a dosage matrix
pi.dosage(dos,L=NULL)
a ni X nl dosage matrix containing the number of derived/alternate alleles each individual carries at each SNP
the length of the sequence
if L=NULL
(default), returns the sum over SNPs of nucleotide diversity;
otherwise return the average nucleotide diversity per nucleotide given the length L
of the sequence