getset.ff {ff}R Documentation

Reading and writing single values (low-level)

Description

The three functions get.ff, set.ff and getset.ff provide the simplest interface to access an ff file: getting and setting single values

Usage

get.ff(x, i)
set.ff(x, i, value, add = FALSE)
getset.ff(x, i, value, add = FALSE)

Arguments

x an ff object
i an index position within the ff file
value the value to write to position i
add TRUE if the value should rather increment than overwrite at the index position

Details

getset.ff combines the effects of get.ff and set.ff in a single operation: it retrieves the old value at position i before changing it. getset.ff will maintain na.count.

Value

get.ff returns a single value, set.ff returns the 'changed' ff object (like all assignment functions do) and getset.ff returns the value at the position. More precisely getset.ff(x, i, value, add=FALSE) returns the old value at the position i while getset.ff(x, i, value, add=TRUE) returns the incremented value of x.

Note

get.ff, set.ff and getset.ff are low level functions that do not support ramclass and ramattribs and thus will not give the expected result with factor and POSIXct

Author(s)

Jens Oehlschlägel

See Also

readwrite.ff for low-level vector access and [.ff for high-level access

Examples

 x <- ff(0, length=12)
 get.ff(x, 3L)
 set.ff(x, 3L, 1)
 x
 set.ff(x, 3L, 1, add=TRUE)
 x
 getset.ff(x, 3L, 1, add=TRUE)
 getset.ff(x, 3L, 1)
 x
 delete(x)
 rm(x)

[Package ff version 2.0.0 Index]