math expressions
Don Wingate wrote:
Dear Uwe (and All R users), The problem is that the vector of names I want to use is created dynamically at a time independent of the plotting. The situation is a bit complex. An object is created, say "object.to.plot" which has as an attribute the vector of names, say "labels.names". This vector of names is created dynamically according to parameter values present when "object.to.plot" is created (using the string manipulating functions, especially paste). When using dotplot on the values associated with this object, I can easily use the names vector for labels. What I want to do is create a vector of math expressions, based on the names vector. Do you think there is a way to do this? More generally, what I need to do is dynamically create a vector of math expressions (using the powers of string manipulation), which can then be used as the textual values for a plot function.
What about something like:
numbers <- 1:2 # the dynamical part
my.names <- NULL
for(i in numbers)
my.names <- c(my.names,
eval(as.expression(substitute(expression(x[i]^2), list(i=i)))))
dotplot(1:2, labels = my.names)
I don't get it without a loop, but for a plot it shouldn't be too
expensive.
Uwe Ligges
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