Load: A layer above the load() function for deserializing RDA files

In duncantl/RDAInfo: Read summary of RDA files and restore individual elements

A layer above the load() function for deserializing RDA files

Description

This function restores a user-specified subset of the variables in an RDA file. It also allows one to remap the variables names in the RDA file to different variables names when restoring the objects. By default, it avoids overwriting existing variables. It returns the names of the loaded variables without making them invisible().

This is a drop-in replacement for load, with the first three arguments being passed directly to load.

This version currently restores all the objects in the RDA file into a temporary environment and then assigning only the ones of interest to the target environment, discarding the other variables. So this is a helper function. The Table-of-Contents (RDAToc) approach allows us to restore just the variables of interest, but with a caveat of not yet fully handling reference objects in the RDA.

Usage

Load(file, envir = parent.frame(), verbose = FALSE, vars = character(), .noOverwrite = TRUE)

Arguments

file	the path to the RDA file, or a connection
envir	the environment into which the objects will be assigned/loaded
verbose	should item names be printed during loading?
vars	a character vector of variable names identifying the variables in the RDA file to restore/load. The elements of this character vector can have a name, e.g., c(x = "a") and the name specifies the new/target variable name to which the value will be assigned. In other words, the values in vars identify the variables in the RDA file; any names on this vector specify the target variables in envir to which they will be assigned.
.noOverwrite	a logical value that controls whether to overwrite any existing variables in envir.

Details

This current calls load and then copies the subset of objects to envir.

Value

a character vector which is the subset of the combination of vars and ... for which the assignment took place.

Author(s)

Duncan Temple Lang

See Also

load

Examples

  #  Create a simple RDA file.
  rda = tempfile()
  a = 1:10
  b = letters[1:5]
  d = mtcars
  save(a, b, d, file = rda)


  # load a and b into a new environment and also ask for non-existent f
  e = new.env()
  Load(rda, e, vars = c("a", xyz = "b", "f"))
  # result shows a and xyz=b, but no f.

  # do it again and we won't overwrite
  Load(rda, e, vars = c("a", xyz = "b"))  

duncantl/RDAInfo documentation built on Aug. 10, 2024, 3:17 p.m.