FDF-class: Class FDF

In privefl/bigdfr: Operate with Data Frames Stored on Disk

Description

A reference class for storing and accessing data frames stored on disk.

Usage

FDF(df, backingfile = tempfile())

Arguments

df	A data frame.
backingfile	Path to the file storing the data on disk. Default stores in the temporary directory.

Details

An FDF object has many field:

• $address: address of the external pointer containing the underlying C++ object, to be used as a XPtr<FDF> in C++ code

• $extptr: use $address instead

• $nrow

• $ncol

• $types

• $backingfile: File that stores the numeric data of the FDF

• $rds: 'rds' file (that may not exist) in which this object is stored

• $is_saved: whether this object stored in $rds?

• $ind_row: Indices of rows for a subview of the FDF

• $ind_col: Indices of columns for a subview view of the FDF

• $strings: 2^16 strings to match with integers (between 0 and 65535)

• $nstr: Number of unique strings already matched with an integer

• $groups: Tibble with position indices of $ind_row for each group.

• $groups_internal: use $groups instead

• $meta: Meta information for factors, dates and character vectors.

And some methods:

• $save(): Save the FDF object in $rds. Returns the FDF.

privefl/bigdfr documentation built on May 20, 2019, 9:39 a.m.