R: Evaluate an expression in a ffdf data environment

within.ffdf {ffbase} | R Documentation

## Evaluate an expression in a ffdf data environment

### Description

Same functionality as `within`. Please note that you should write your expression as if it is a normal `data.frame`. The resulting data.frame however will be a new `ffdf` data.frame.

### Usage

    ## S3 method for class 'ffdf'
    within(data, expr, ...)

### Arguments

`data` | `ffdf` data object used as an environment for evaluation.
`expr` | expression to evaluate.
`...` | arguments to be passed to `chunk`.

### Value

a modified clone of `data`.

### Examples

    ffdat <- as.ffdf(data.frame(x=1:10, y=10:1))
    # add z to the ffdat
    within(ffdat, {z <- x+y})

[Package ffbase version 0.13.1 Index]