An S3 class for representing information on massive SNP arrays.
A named list with at least 4 slots:
A FBM.code256 which is
a special Filebacked Big Matrix encoded with type
raw (one byte
unsigned integer), representing genotype calls and possibly imputed
allele dosages. Rows are individuals and columns are SNPs.
data.frame containing some information on the SNPs
(read from a ".fam" file).
data.frame giving some information on the individuals
(read from a ".bim" file).