compute_seb_proj_var: analytically compute the variance of a projection given a...
In ollyburren/cupcake: PCA for GWAS

analytically compute the variance of a projection given a standard error of beta for a given trait compute_seb_proj_var

compute_seb_proj_var(
  gwas.DT,
  shrink.DT,
  man.DT,
  w.DT,
  ref_gt_dir,
  method = "shrinkage",
  quiet = FALSE
)

`gwas.DT`	a data.table - variants and summary statistics
`shrink.DT`	a data.table - as returned by `compute_shrinkage_metrics`
`man.DT`	a data.table - snp manifest file that maps snps to ld.block
`w.DT`	a data.table - a data table of weights/rotations from a basis first column is 'pid' and subsequent columns for each principal component.
`ref_gt_dir`	scalar - path to a dir of R objects named CHR_1kg.RData containing reference GT in snpMatrix format
`method`	scalar - shrinkage method to use (default shrinkage) but also valid is none
`quiet`	a scalar - boolean whether to show progress messages