Setting Environments

loading *.rda files to non-.GlobalEnv

Suppose there is a *.rda file which contains x and y variables.

x <- 1:5
y <- 10:20
save(x, y, file="xy.rda")

Further, suppose in a different session, we have x and y variables defiend in the global workspace.

x <- 100
y <- 200

If we try to load x and y variables from xy.rda here, it will accidently overwrite current x and y in the global workspace. There are couple of ways to put loaded objects to separate place in the search path.

# ex1
env1 <- new.env()
g <- load("xy.rda", envir=env1)
get(g[1], env1)
[1] 1 2 3 4 5
get(g[2], env1)
 [1] 10 11 12 13 14 15 16 17 18 19 20
mget(ls(env1), env1)
$x
[1] 1 2 3 4 5

$y
 [1] 10 11 12 13 14 15 16 17 18 19 20
# x and y in the global environment (not overwritten)
x
[1] 100
y
[1] 200

# ex2
env2 <- local({load("xy.rda"); environment()})
env2$x
[1] 1 2 3 4 5
env2$y
 [1] 10 11 12 13 14 15 16 17 18 19 20
# x and y in the global environment (not overwritten)
x
[1] 100
y
[1] 200

# ex3
env3 <- attach(NULL, pos=2, name="myenv")
load("xy.rda", envir=env3)
env3$x
[1] 1 2 3 4 5
env3$y
 [1] 10 11 12 13 14 15 16 17 18 19 20
  
search()
 [1] ".GlobalEnv"        "myenv"             "package:stats"    
 [4] "package:graphics"  "package:grDevices" "package:utils"    
 [7] "package:datasets"  "package:fortunes"  "package:methods"  
[10] "Autoloads"         "package:base"     
detach()
search()
 [1] ".GlobalEnv"        "package:stats"     "package:graphics" 
 [4] "package:grDevices" "package:utils"     "package:datasets" 
 [7] "package:fortunes"  "package:methods"   "Autoloads"        
[10] "package:base"

# x and y in the global environment (not overwritten)
x
[1] 100
y
[1] 200

# ex4
env4 <- attach("xy.rda")
The following object(s) are masked _by_ '.GlobalEnv':

    x, y
env4$x
[1] 1 2 3 4 5
env4$y
 [1] 10 11 12 13 14 15 16 17 18 19 20
ls(pos=2)
[1] "x" "y"
search()
 [1] ".GlobalEnv"        "file:xy.rda"       "package:stats"    
 [4] "package:graphics"  "package:grDevices" "package:utils"    
 [7] "package:datasets"  "package:fortunes"  "package:methods"  
[10] "Autoloads"         "package:base"     
detach()
search()
 [1] ".GlobalEnv"        "package:stats"     "package:graphics" 
 [4] "package:grDevices" "package:utils"     "package:datasets" 
 [7] "package:fortunes"  "package:methods"   "Autoloads"        
[10] "package:base"     

# x and y in the global environment (not overwritten)
x
[1] 100
y
[1] 200