Produces a graphical display, as a heat map, of measures of pairwise linkage disequilibria between SNPs. Users may optionally include the physical locations or genetic map distances of each SNP on the plot. Users should note that the imported package 'snpStats' and the suggested packages 'rtracklayer', 'GenomicRanges', 'GenomInfoDb' and 'IRanges' are all BioConductor packages < https://bioconductor.org>.