dput does not work with data.table

[Christoph_Jae]

Hi together,

while trying to write a minimal example for a problem that is bothering me, I discoverd that dput() does not work on data.tables. More precisely, the output of dput cannot be read in, most probably because the ".internal.selfref = <pointer: ..." syntax causes problems:

library(data.table)
DT <- data.table(A=1:2, B=2:3)
dput(DT)
structure(list(A = 1:2, B = 2:3),
          .Names = c("A", "B"),
          row.names = c(NA, -2L),
          class = c("data.table", "data.frame"),
          .internal.selfref = <pointer: 0x0000000000150788>)

Trying to read the structure part gives: "Error: unexpected '<' in:
"          class = c("data.table", "data.frame"),
          .internal.selfref = <"

Are there any workarounds? If not, is this a base-R problem or a data.table specific problem?

Thanks Christoph

[Christoph_Jae]

Follow-up: Putting <pointer:...> in quotation marks works:

structure(list(A = 1:2, B = 2:3),
          .Names = c("A", "B"),
          row.names = c(NA, -2L),
          class = c("data.table", "data.frame"),
          .internal.selfref = "<pointer: 0x0000000000150788>")

But why is that not inserted in the first place? Does that break something else?

[Matthew Dowle]

Hi. You can include the <pointer:...> part when posting, we know what is
meant and can fix it up if we need to.  It's an R thing, from ?deparseOpts
:

"
warnIncomplete
Some exotic objects such as environments, external pointers, etc. can not
be deparsed properly. This option causes a warning to be issued if the
deparser recognizes one of these situations.

Using control = "all" comes closest to making deparse() an inverse of
parse(). However, not all objects are deparse-able even with this option.
A warning will be issued if the function recognizes that it is being asked
to do the impossible.
"

> Follow-up: Putting <pointer:...> in quotation marks works:
>
> structure(list(A = 1:2, B = 2:3),
>           .Names = c("A", "B"),
>           row.names = c(NA, -2L),
>           class = c("data.table", "data.frame"),
>           .internal.selfref = "<pointer: 0x0000000000150788>")
>
> But why is that not inserted in the first place? Does that break something
> else?
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/dput-does-not-work-with-data-table-tp4519150p4519172.html
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[Christoph_Jae]

OK, thanks. Good to know it's not my lack of knowledge this time ;-)