> On Dec 23, 2016, at 12:45 PM, Carl Sutton via R-help <r-help@r-project.org>
> wrote:
>
> Merry Christmas and Happy Holidays
>
> I am attempting to use dput and or dget to send data along with a help
> request to another list (package specific). Read the help pages for both
> and they appeared to be fairly simple functions. Found an example on github
> and it appeared to be an easy task to replicate. Alas, a copy and paste of
> the github example worked but my toy data example did not.
>
> # dput and dget functions
> # Example from github
> set.seed(1337)
> NN <- 10
> theData <- data.frame(Alpha = rnorm(NN),
> Beta = rnorm(NN))
> theData$Gamma <- theData$Alpha * 2 + theData$Beta / 2 + rnorm(NN)
> dput(theData, "temporary_file")
> theDataReconstitutedAgain <- dget("temporary_file")
> print(theDataReconstitutedAgain)
>
>
> # try it with my "toy data"library(data.table)
This is a guess based on what I know about data.table-objects and how they are
represented with dput. You will see an .internal.selfref = <pointer:
0x7f7fd18f2778>
But if you try to assign the value of the dput output to an R name, it's going
to fail. You need to remove the .internal.selfref = <pointer: 0x7f7fd18f2778>
and then assign as a data frame and run setDT() on the name.
> library(tidyr)
> # data table for melt and columns split
> dt1 <- data.table(a_1 = 1:10, b_2 = 20:29,folks = c("art","brian","ed",
> "rich","dennis","frank", "derrick","paul","fred","numnuts"),
> a_2 = 2:11, b_1 = 21:30)
> melted <- melt(dt1, id = "folks")[,c("varType","varIndex") :=
> tstrsplit(variable,"_")][,variable:=NULL]
Run this:
dput(melted)
> # melted has 40 observations from stacking a and b variables
> # which have lengths of 20 each
> # here cometh the frustrtion
> dput(melted,"temp_file.txt")
> goGetIt <- dget("temp_file.txt", keep.source = FALSE)
> print(goGetIt)
>
>
>> goGetIt <- dget("temp_file.txt", keep.source = FALSE)
> Error in parse(file = file, keep.source = keep.source) :
> temp_file.txt:18:36: unexpected '<'
That's because the regular R parser doesn't recognize the pointer as valid R
code. It was not designed to recognize data.tables. the tidyr functions are
designed to return data.frames, but `dget` is not from a package that is
"data.table-aware"
> 17: "varIndex"), row.names = c(NA, -40L), class = c("data.table",
> 18: "data.frame"), .internal.selfref = <
> ^
>> print(goGetIt)
> Error in print(goGetIt) : object 'goGetIt' not found
>>
Try this instead:
dput(as.data.frame(melted),"temp_file.txt")
goGetIt <- dget("temp_file.txt", keep.source = FALSE)
setDT(goGetIt)
print(goGetIt)
--
David.
> the help page states dput just writes an ASCII text representation of an R
> object to a file or connection, or uses one to recreate the object. Nothing
> there about not allowing a data frame or data table and the github example
> was a data frame. The line numbers referenced do not appear to refer to my
> code (but maybe they do and I am ignorant of the meaning) and the code works
> up to the dget line.
>
> Typing dget in the console to see the inner workings of the function was not
> helpful.
>
> Also, I am unclear as to just how dput and dget work. If I save a subset of
> actual data to an object, then do dput on that object, can I rely that
> whomever I send my code to (which includes the dput statement) be able to
> retrieve the data? In other words, dput saves the data in the code file?
>
> Thanks for your help and may the holidays be wonderful for you and your loved
> one.
> Carl Sutton
>
> ______________________________________________
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