A helper function to add predictors to a filebacked matrix of data
add_predictors(obj, add_predictor, id_var, rds_dir, quiet)A list of 2 components:
'obj' - a bigSNP object with an added element representing the matrix that includes the additional predictors as the first few columns
'non_gen' - an integer vector that ranges from 1 to the number of added predictors. Example: if 2 predictors are added, unpen= 1:2
A bigSNP object
Optional: add additional covariates/predictors/features from an external file (i.e., not a PLINK file).
String specifying which column of the PLINK .fam file has the unique sample identifiers.
The path to the directory in which you want to create the new '.rds' and '.bk' files. Defaults to data_dir(from process_plink() call)
Logical: should messages be printed to the console? Defaults to FALSE (which leaves the print messages on...)