dumpObjects {filehash} | R Documentation |
Dump objects of database
Description
Dump R objects to a filehash database
Usage
dumpObjects(..., list = character(0), dbName, type = NULL, envir = parent.frame())
dumpImage(dbName = "Rworkspace", type = NULL)
dumpDF(data, dbName = NULL, type = NULL)
dumpList(data, dbName = NULL, type = NULL)
dumpEnv(env, dbName)
Arguments
... |
R objects to dump |
list |
character vector of names of objects to dump |
dbName |
character, name of database to which objects should be dumped |
type |
type of database to create |
envir |
environment from which to obtain objects |
data |
a data frame or a list |
env |
an environment |
Details
Objects dumped to a database can later be loaded via dbLoad
or
can be accessed with dbFetch
, dbList
, etc.
Alternatively, the with
method can be used to evaluate code in
the context of a database. If a database with name dbName
already exists, objects will be inserted into the existing database
(and values for already-existing keys will be overwritten).
dumpDF
is different in that each variable in the data frame is
stored as a separate object in the database. So each variable can be
read from the database separately rather than having to load the
entire data frame into memory. dumpList
works in a simlar
way.
The dumpEnv
function takes an environment and stores each
element of the environment in a filehash
database.
Value
An object of class "filehash"
is returned and a database is
created.
Author(s)
Roger D. Peng
Examples
data <- data.frame(y = rnorm(100), x = rnorm(100), z = rnorm(100))
db <- dumpDF(data, dbName = "dataframe.dump")
fit <- with(db, lm(y ~ x + z))
summary(fit)
dbUnlink(db)
db <- dumpList(list(a = 1, b = 2, c = 3), "list.dump")
db$a
dbUnlink(db)