[R] R GUI and object browser
dputler at scu.edu
Wed Jul 17 07:41:39 CEST 2002
Actually, it is fairly easy to give certain objects (those with a mode of
"list", which includes data frames) a date attribute. This can be done
either after creating a list object and then providing its date attribute, or
(in at least some instances) by modifying the function that creates that
object to include the date attribute assignment. The two functions needed to
do this are the attr() and date().
Here is an example of doing this after the fact:
mydata <- data.frame(1:10,11:20)
attr(mydata, "create.date") <- date()
You can then get the value of the create.date attribute using the command
Which will return a character string along the lines of
"Tue Jul 16 22:12:05 2002"
Moreover, my guess is that R functions that work on data frames will simply
ignore the create.date attribute, or so my limited testing suggests.
Modifying functions that create list objects often isn't hard either (although
I don't know if this is always the case, but suspect it is). It turns out
that the last two assignment statements of the data.frame() function are:
attr(value, "row.names") <- row.names
attr(value, "class") <- "data.frame"
where "value" is the internal variable name for the data frame within the
data.frame() function. If you modify the data.frame() function by adding the
attr(value, "create.date") <- date()
after the assignment of the "class", any data frames created using this
function will have a create.date attribute.
On Tuesday 16 July 2002 03:23 pm, Patrick Connolly wrote:
> On Mon, 15-Jul-2002 at 01:13AM -0700, Dan Putler wrote:
> |> As part of the obveRsive GUI project, we've written a function with
> |> much of the functionality that Patrick Connolly was suggesting
> |> (which is a bit more compact than the output from ls.str()). Alas,
> |> no date capabilities.
> My method of getting the dates is somewhat inelegant. However, it
> could be simple if there was a date attribute of objects. Would such
> a thing create an overhead that could be too burdensome for people who
> don't have a use for it? Perhaps it could be one of the general
> options that users could customize.
> |> The function is call ls.objects(), and example output appears below:
> |> Object.Name Object.Mode Object.Type Observations Variables
> |> 1 ccsest.df list data.frame 800 21
> |> 2 ccsval.df list data.frame 800 21
> |> 3 junkfactor numeric factor 100 1
> |> 4 junklist list unknown - -
> |> 5 junkmat numeric matrix 100 2
> |> 6 junkmodel list lm - -
> |> 7 ls.objects function function - -
> |> 8 orderdf function function - -
> |> 9 pkg character vector 1 1
> |> 10 stuff list data.frame 12 2
> |> 11 try numeric vector 100 1
> |> 12 try1 numeric vector 100 1
> |> 13 try2 numeric vector 100 1
> |> 14 trydat list data.frame 100 2
> |> 15 tryname character vector 1 1
> This is certainly less complicated than my approach and does some
> things mine doesn't.
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