[R] Dating Objects

[David Whiting]

Hi Jason,

Perhaps you get do what you want to do using attributes? Does this get
close to what you need?


> ## Create some objects
> xx <- "adsfasdf"
> zz <- 3027
> yy <- "abdsf"
>
> ## Assign a time attribute to them.
> attr(zz, "time") <- Sys.time()
> attr(yy, "time") <- Sys.time()
>
> ## To see the time attribute of, for example, zz:
> attributes(zz)$time
[1] "2005-08-12 16:46:47 BST"
>
> ## A crude function to show the time attributes
> ## of objects:
>
> time.attr <- function (x) {
+   x.attr <- attributes(get(x))
+   attr.names <- names(attributes(get(x)))
+   if (!is.null(attr.names) && attr.names %in% "time") {
+     x.time <- x.attr$time
+     names(x.time) <- x
+     x.time
+   }
+ }
>
> ## Apply the time.attr function to all objects listed by ls():
> lapply(ls(), time.attr)
[[1]]
NULL

[[2]]
NULL

[[3]]
                       yy
"2005-08-12 16:46:47 BST"

[[4]]
                       zz
"2005-08-12 16:46:47 BST"


Dave



Jason Skelton wrote:
> Hi
> 
> I know this subject has been mentioned before but from the mail archives 
> I'm under the impression that this is not possible ?
> I'm trying to carryout the equivalent of ls -l in R to give some 
> date/time label to each of my objects
> 
> If the case is that there is no equivalent, is it possible to list all 
> objects in an environment that share a common component ?
> So that the common component is also displayed ?
> 
> I'm attempting to do the following
> 
> object$time <- Sys.time() for every object i've created
> which although tedious appears to work
> 
> However I've no idea how if it is possible to list all the objects by $time
> or extract the object name & $ time from all objects simultaneously so I 
> can compare them.
> Or am I just wasting my time ?
> 
> Apologies but my knowledge of R is limited at best ;-(
> Any help would be fantastic and greatfully received
> 
> Cheers
> 
> Jason
> 
> 
> 

-- 
David Whiting
School of Clinical Medical Sciences, The Medical School
University of Newcastle upon Tyne, NE2 4HH, UK.

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