filehash (version 2.4-2)

dumpObjects: 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

Value

An object of class "filehash" is returned and a database is created.

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.

Examples

# NOT RUN {
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)

db <- dumpList(list(a = 1, b = 2, c = 3), "list.dump")
db$a
# }