[R] Stacked density plots

[Judith Flores]

Hello R-community,

    I want to generate stacked density plots in lattice. My data consist of a numeric variable ('pid') that is measured in different individuals ('id'), which can be divided in two types ('type') and the measurements were repeated a different time points ('day').

I read in the Lattice book that this can be done using the 'flowViz' package, so I tried to reproduce the example given in there and obtained an error:

library('flowViz')
data(GvHD, package='flowCore")
densityplot(Visit~'FSC-H'|Patient, data=GvHD)

Error: ' "FSC-H" ' is/are no valid parameter(s) in this frame

    I am not sure if I am missing something. I was hoping to apply something similar to my data, maybe like this?

desityplot(id~pid|type+day, data=mydata)

Thank you in advance for your help,

Judith