object
An object of class "MSnExp"
or a
data.frame
. In the latter case, the data frame must have numerical
columns named 'retention.time' and 'precursor.mz' and one of 'tic',
'file', 'peaks.count' or 'charge', depending on the z
parameter. Such a data frame is typically generated using the
header
method on "MSnExp"
object.
z
A character indicating according to what variable to colour
the dots. One of, possibly abreviated, "ionCount" (total ion count),
"file" (raw data file), "peaks.count"
(peaks count) or "charge" (precursor charge).