Restore Objects from a Datastore

2.2.3.5.6 Restore Objects from a Datastore

The ore.load function restores R objects saved in a datastore to the R global environment, .GlobalEnv.

The function returns a character vector that contains the names of the restored objects.

You can load all of the saved objects or you can use the list argument to specify the objects to load. With the envir argument, you can specify an environment in which to load objects.

Example 2-22 Using the ore.load Function to Restore Objects from a Datastore

This example demonstrates using the ore.load function to restore objects from datastores that were created in Example 2-20. The example runs in the same R session as that example.

# List the R objects.
ls()

# List the datastores.
ore.datastore()

# Delete the x and z objects.
rm(x, z)
ls()

# Restore all of the objects in datastore ds2.
ore.load("ds2")

ls()

# After ending the R session and starting another session.
ls()
# The datastore objects persist between sessions.
ore.datastore()

# Restore some of the objects from datastore ds1.
ore.load("ds1", list = c("df1", "df2", "iris_of"))
ls()

Listing for Example 2-22

R> # List the R objects.
R> ls()
[1] "df1"     "df2"     "iris_of" "x"       "y"       "z"
R> 
R> # List the datastores.
R> ore.datastore()
  datastore.name object.count size       creation.date  description
1     another_ds            3 1243 2014-07-24 13:31:56 For pattern mattching
2          dfobj            2  656 2014-07-24 13:31:46            df objects
3            ds1            4 3162 2014-07-24 13:25:17          My datastore
4            ds2            2 1111 2014-07-24 13:27:26                only x
R> 
R> # Delete the x and z objects.
R> rm(x, z)
R> ls()
[1] "df1"     "df2"     "iris_of" "y"
R> 
R> # Restore all of the objects in datastore ds2.
R> ore.load("ds2")
[1] "x" "z"
R> 
R> ls()
[1] "df1"     "df2"     "iris_of" "x"       "y"       "z"
R> 
R> # After ending the R session and starting another session.
R> ls()
character(0)
R> # The datastore objects persist between sessions.
R> ore.datastore()
  datastore.name object.count size       creation.date           description
1     another_ds            3 1243 2014-07-24 13:31:56 For pattern mattching
2          dfobj            2  656 2014-07-24 13:31:46            df objects
3            ds1            4 3162 2014-07-24 13:25:17          My datastore
4            ds2            2 1111 2014-07-24 13:27:26                only x

R> # Restore some of the objects from datastore ds1.
R> ore.load("ds1", list = c("df1", "df2", "iris_of"))
[1] "df1"     "df2"     "iris_of"
R> ls()
[1] "df1"     "df2"     "iris_of"

Parent topic: Save and Manage R Objects in the Database