如何从Rdata文件分配数据帧

Question

I have a data.frame in the following directory "/..../1_5_setpoint.Rdata".

The name of the data frame is "setpoint" and the name of the file is "1_5_setpoint". I want to create a data.frame with the name "1_5_setpoint". This is my code:

  assign("1_5_setpoint",  get(load("/..../1_5_setpoint.Rdata")))

The problem is that I end up having to data frames in memory: one called "setpoints" (I don't want this one) and one called "1_5_setpoint" (I want this one).

This could cause a problem if the data is very big.

Any suggestions?

Answer 1

It would be easier if you would save your data as RDS not Rdata , you could then simply load it to an object with a desired name:

saveRDS(mtcars, "mtcars.rds")
cars <- readRDS("mtcars.rds")

Rdata files are used to store all objects you created, have a look at this explanation . As discussed here RDS is batter solution for storing single objects.

Answer 2

@Konrad is correct about RDS being the right solution. Sometimes, you don't have the option of getting an RDS file and you only get a .RData file. In that case, the simplest method I know of is to load the data using a function and either return the only variable within or allow selection of the variable to return.

An example there could be:

myLoad <- function(filename, variable) {
  tmp.env <- new.env()
  varnames <- load(filename, envir=tmp.env)
  if (missing(variable)) {
    ## Choose the variable name as the only variable in the file or
    ## give an error.
    if (length(varnames) == 1) {
      return(get(varnames, envir=tmp.env))
    } else {
      stop("More than one variable present in the file, please specify which variable to extract.  Choices are: ",
           paste(varnames, sep=", "))
    }
  } else {
    return(get(variable, envir=tmp.env))
  }
}

ls()
save(mtcars, file="mtcars.RData")
mtcars_1_5 <- myLoad("mtcars.RData")
identical(mtcars, mtcars_1_5)
ls()