This index is used by plot.rppca to downsample the col (colour) values. It is stored in the rppca object's ds slot.
dspc(pc, to = 10000)An (invisible) object of class rppca with a slot ds added.
an object of class rppca
The down-sampling parameter. A numeric > 0 or a vector or NA. Interpreted as a proportion or integer or a index vector, see details.
The parameter to is used to specify and possibly which individuals are sampled.
If NA, all individuals are retained. If to is of length one and is between 0 and 1,
then it is interpreted as a proportion. If it is greater than 1, it is taken to be
the number of individuals to be sampled (possibly rounded by sample.int). If
to is a logical or an integer vector, it is used for logical or integer indexing, respectively.
The integer indices of the sample individuals are written to the ds slot.
If ds exists, it is overwritten with a warning.