toplot
Biological group to be plotted (features not belonging to that group are discarded).
It may be a number or a text with the name of the biological group.
If toplot=1 or toplot="global", all features are used for the plot.
samples
Samples (or conditions) to be plotted. If NULL, all the samples are plotted.
If samples > 2, only a descriptive plot will be generated. If not, diagnostic plots will be obtained showing both the R-squared and model p-value
from the spline regression model describing the relationship between the length and the expression.