Thanks, Duncan In my context, the following gives me what I want:
> foo.glm <- function(object) {
+ if (typeof(substitute(object))=="symbol")
+ oname <- as.character(sys.call())[2]
+ else oname <- NULL
+ oname
+ }
>
>
>
> indep <- glm(Freq ~ mental + ses, family = poisson, data = Mental)
> foo.glm(indep)
[1] "indep"
>
> foo.glm(glm(formula = Freq ~ mental + ses, family = poisson, data =
Mental))
NULL > Duncan Murdoch wrote:
On 16/03/2010 8:26 AM, Michael Friendly wrote:In a function, say foo.glm for glm objects I want to use the name of the object as a label for some output, but *only* if a glm object was passed as an argument, not a call to glm() producing that object.How can I distinguish these two cases?Look at typeof(substitute(object)). For example, > f <- function(object) typeof(substitute(object)) > f(aname) [1] "symbol" > f(aname+1) [1] "language"That will tell you if an object was passed by name, or if you got an expression to produce the object.One problem with this approach is that it only looks at the direct call to f, for example> g <- function(x) f(x) > g(aname + 1) [1] "symbol" because substitute looks at the f(x) call, not the g(aname + 1) call. Duncan MurdochFor example, I can use the following to get the name of the argument: foo.glm <- function(object) { oname <- as.character(sys.call())[2] oname } > indep <- glm(Freq ~ mental + ses, family = poisson, data = Mental) > foo.glm(indep) [1] "indep" But in foo.glm() I want to avoid using this as oname:> foo.glm(glm(formula = Freq ~ mental + ses, family = poisson, data = Mental)) [1] "glm(formula = Freq ~ mental + ses, family = poisson, data = Mental)"Here is Mental, if it matters. dput(Mental) structure(list(ses = structure(c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 6L), .Label = c("1", "2", "3", "4", "5", "6"), class = c("ordered", "factor")), mental = structure(c(1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L,4L), .Label = c("Well", "Mild", "Moderate", "Impaired"), class = c("ordered","factor")), Freq = c(64L, 94L, 58L, 46L, 57L, 94L, 54L, 40L, 57L, 105L, 65L, 60L, 72L, 141L, 77L, 94L, 36L, 97L, 54L, 78L,21L, 71L, 54L, 71L)), .Names = c("ses", "mental", "Freq"), row.names = c(NA,-24L), class = "data.frame")
--Michael Friendly Email: friendly AT yorku DOT ca Professor, Psychology Dept.
York University Voice: 416 736-5115 x66249 Fax: 416 736-5814 4700 Keele Street http://www.math.yorku.ca/SCS/friendly.html Toronto, ONT M3J 1P3 CANADA ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
