Iterative Extrapolation of Species' Haplotype Accumulation Curves for Genetic Diversity Assessment R package HACSim version 1.0.7-1 Performs iterative extrapolation of species' haplotype accumulation curves using a nonparametric stochastic (Monte Carlo) optimization method for assessment of specimen sampling completeness based on the approach of Phillips et al. (2015) <doi:10.1515/dna-2015-0008>, Phillips et al. (2019) <doi:10.1002/ece3.4757> and Phillips et al. (2020) <doi: 10.7717/peerj-cs.243>. 'HACSim' outputs a number of useful summary statistics of sampling coverage ("Measures of Sampling Closeness"), including an estimate of the likely required sample size (along with desired level confidence intervals) necessary to recover a given number/proportion of observed unique species' haplotypes. Any genomic marker can be targeted to assess likely required specimen sample sizes for genetic diversity assessment. The method is particularly well-suited to assess sampling sufficiency for DNA barcoding initiatives. Users can also simulate their own DNA sequences according to various models of nucleotide substitution. A Shiny app is also available. Software Imports: ape (>= 5.3), data.table (>= 1.12.8), graphics (>= 3.6.1), matrixStats (>= 0.56.0), pegas (>= 0.13), Rcpp (>= 1.0.3), stats (>= 3.6.1), stringr (>= 1.5.0), utils (>= 3.6.1) LinkingTo: Rcpp, RcppArmadillo Jarrett D. Phillips <phillipsjarrett1@gmail.com> Comprehensive R Archive Network (CRAN) Jarrett D. Phillips [aut, cre], Steven H. French [ctb], Navdeep Singh [ctb] GPL-3 2025-09-19 application/tgz https://CRAN.R-project.org/package=HACSim doi:10.32614/CRAN.package.HACSim