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Simpe low-level interface for reading and writing vectors from ff files.
read.ff(x, i, n)
write.ff(x, i, value, add = FALSE)
readwrite.ff(x, i, value, add = FALSE)
an ff object
a start position in the ff file
number of elements to read
vector of elements to write
TRUE if the values should rather increment than overwrite at the target positions
read.ff
returns a vector of values, write.ff
returns the 'changed' ff object (like all assignment functions do) and readwrite.ff
returns the values at the target position.
More precisely readwrite.ff(x, i, value, add=FALSE)
returns the old values at the position i
while readwrite.ff(x, i, value, add=TRUE)
returns the incremented values of x
.
readwrite.ff
combines the effects of read.ff
and write.ff
in a single operation: it retrieves the old values starting from position i
before changing them.
getset.ff
will maintain na.count
.
getset.ff
for low-level scalar access and [.ff
for high-level access
# NOT RUN {
x <- ff(0, length=12)
read.ff(x, 3, 6)
write.ff(x, 3, rep(1, 6))
x
write.ff(x, 3, rep(1, 6), add=TRUE)
x
readwrite.ff(x, 3, rep(1, 6), add=TRUE)
readwrite.ff(x, 3, rep(1, 6))
x
rm(x); gc()
# }
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