object
An object of class "MSnExp"
or and
'data.frame'. In the latter case, the data frame must have numerical
columns named 'charge' and one of 'precursor.mz', 'peaks.count' or 'ionCount',
depending on the z
parameter.
Such a data frame is typically generated using the
header
method on "MSnExp"
object.
z
A character indicating which parameter's densitiy to plot.
One of, possibly abreviated, "ionCount" (total ion count),
"peaks.count" (peaks count) or "precursor.mz" (precursor MZ).