load() into a data frame with my chosen name => .ThisEnv ?

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very simple question.  I probably forgot the answer (early stage onset),
and I could not find it via google and r-help.

I have a number of files, each containing one saved data frame.  I want to
do the equivalent of

   d <- .GlobalEnv[[ load(file="dxxxx.Rdata") ]
Did you try using load's 'envir' argument, which should be mentioned in its help file?
E.g., define the function
   getMyData <- function(RDataFile) {
       # RDataFile should be *.RData file containing exactly one object
       .ThisEnv <- new.env(parent = emptyenv())
       loadedNames <- load(file=RDataFile, envir=.ThisEnv)
       stopifnot(length(loadedNames)==1)
       .ThisEnv[[ loadedNames ]]
   }
and use it in the loop as
  d <- getMyData(RDataFile = fname)

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of ivo welch
Sent: Monday, June 17, 2013 4:08 PM
To: r-help
Subject: [R] load() into a data frame with my chosen name => .ThisEnv ?

very simple question.  I probably forgot the answer (early stage onset),
and I could not find it via google and r-help.

I have a number of files, each containing one saved data frame.  I want to
do the equivalent of

   d <- .GlobalEnv[[ load(file="dxxxx.Rdata") ]

but inside a function, and I don't need the original name (dxxxx).  in the
end, I want to do something like

   run <- function( i ) {
        fname <- paste0( "d", i, ".Rdata")
        stopifnot( length(fname)==1 )
        d <- .ThisEnv[[ load(file=fname) ]]
        coef( lm(d[,1] ~ d[,2]) )  ## calculate two coefficients and return
them
   }

   results <- mclapply( 1:10000, run )

stumped over something that should be easy...pointer appreciated.

/iaw
----
Ivo Welch (ivo.welch at gmail.com)

	[[alternative HTML version deleted]]

______________________________________________
R-help at 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.
For your problem, you might want to use saveRDS and readRDS instead of
save and load. I would also use dir to get a list of files rather
than paste. 

Then your solution might look like:

run <- function(filename) {
    df <- readRDS(filename);
    coef( lm(df[,1] ~ df[,2]) ) 
}

results <- lapply( dir(pattern=glob2rx('d*.rds')), run)

If this is disk-bound, using multiple threads probably won't help much.
You'll have to try it out for yourself.

-nfultz
very simple question.  I probably forgot the answer (early stage onset),
and I could not find it via google and r-help.

I have a number of files, each containing one saved data frame.  I want to
do the equivalent of

   d <- .GlobalEnv[[ load(file="dxxxx.Rdata") ]

but inside a function, and I don't need the original name (dxxxx).  in the
end, I want to do something like

   run <- function( i ) {
        fname <- paste0( "d", i, ".Rdata")
        stopifnot( length(fname)==1 )
        d <- .ThisEnv[[ load(file=fname) ]]
        coef( lm(d[,1] ~ d[,2]) )  ## calculate two coefficients and return
them
   }

   results <- mclapply( 1:10000, run )

stumped over something that should be easy...pointer appreciated.

/iaw
----
Ivo Welch (ivo.welch at gmail.com)

	[[alternative HTML version deleted]]

______________________________________________
R-help at 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.