Hi,
I often use plotmeans() from the gplots package to quickly visualize a
pattern of change. I would like to be able to plot separate lines for
different groups, but the function gives an error when a grouping
variable is included in the formula argument.
For instance,
> require(gplots)
> x <- data.frame(Score=rnorm(100), Time=rep(1:10, 10),
Group=factor(rep(c("A","B"),50)))
> plotmeans(Score ~ Time, x) #works fine
> plotmeans(Score ~ Time * Group, x)
Error in .subset2(x, i, exact = exact) :
attempt to select more than one element
> plotmeans(Score ~ Time | Group, x)
Error in ns - 1 : non-numeric argument to binary operator
In addition: Warning message:
In Ops.factor(Time, Group) : | not meaningful for factors
The help for plotmeans() states that it accepts a formula object
including a grouping variable. There is no other grouping argument
listed. Any help is appreciated, including pointing to a more robust
function for plotting means.
Thanks,
Jon