tbl-ffdf: Create a ffdf tbl object

In edwindj/ffbase2: Dplyr for 'ff'

Description

This wraps a 'normal' ffdf object so it can be used with dplyr. It also allows for storing ffdf object in directories/src or retrieving a specific ffdf from a source.

Usage

tbl_ffdf(data, src = getOption("fftempdir"),
  name = deparse(substitute(data)), ...)

## S3 method for class 'ffdf'
as.tbl(x, ...)

## S3 method for class 'tbl_ffdf'
tbl_vars(x)

## S3 method for class 'ffdf'
tbl_vars(x)

## S3 method for class 'tbl_ffdf'
as.data.frame(x, row.names = NULL, optional = FALSE, ...)

## S3 method for class 'tbl_ffdf'
print(x, ..., n = NULL)

## S3 method for class 'tbl_ffdf'
head(x, n = 6L, ...)

## S3 method for class 'tbl_ffdf'
tail(x, n = 6L, ...)

Arguments

data	a ffdf data.frame, will be converted to ffdf using as.ffdf
src	(optional), if a directory name is specified then the ffdf will be saved there
name	table to be loaded
...	not used
x	any R object.
row.names	NULL or a character vector giving the row names for the data frame. Missing values are not allowed.
optional	logical. If TRUE, setting row names and converting column names (to syntactic names: see make.names) is optional.
n	restrict number of rows to n

Details

When data and src are specified a copy_to will be executed. When src and from are specified an ffdf will be loaded from disk. When data is specified without src a temporary ffdf will be created in fftempdir.

Examples

ds <- tbl_ffdf(mtcars)
ds

edwindj/ffbase2 documentation built on May 15, 2019, 11:05 p.m.