This function creates internally the incidence matrices for specific locations when using mmer2.
Usage
at(x, levs)
Arguments
x
a column of a dataframe.
levs
levels of the columns to keep after using the model.matrix() function.
Value
$dd
an incidence matrix with columns for the specific levels specified.
References
Covarrubias-Pazaran G (2016) Genome assisted prediction of quantitative traits using the R package sommer. PLoS ONE 11(6): doi:10.1371/journal.pone.0156744