ffbase (version 0.12.8)

with.ffdf: Evaluate an expression in a ffdf data environment

Description

Evaluate an R expression in an environment constructed from a ffdf data frame. (see with). Please note that you should write your expression as if it is a normal data.frame. The resulting return value however will be a ff object.

Usage

# S3 method for ffdf
with(data, expr, ...)

Arguments

data

ffdf data object used as an environment for evaluation.

expr

expression to evaluate.

...

arguments to be passed to chunk.

Value

if expression is a vector a newly created ff vector will be returned otherwise if the expression is a data.frame a newly created ffdf object will be returned.

See Also

ffdfwith

Examples

# NOT RUN {
dat <- data.frame(x=1:10, y=10:1)

ffdat <- as.ffdf(dat)

with(ffdat, {x+y})
# }