R: Fast data frame input

read.csv.raw {iotools} | R Documentation

## Fast data frame input

### Description

A fast replacement of `read.csv` and `read.delim` which pre-loads the data as a raw vector and parses without constructing intermediate strings.

### Usage

    read.csv.raw(file, header=TRUE, sep=",", skip=0L, fileEncoding="",
                  colClasses, nrows = -1L, nsep = NA, strict=TRUE,
                  nrowsClasses = 25L, quote="'\"")

    read.delim.raw(file, header=TRUE, sep="\t", ...)

### Arguments

`file` | A connection object or a character string naming a file from which to read data.
`header` | logical. Does a header row exist for the data.
`sep` | single character: field (column) separator.
`skip` | integer. Number of lines to skip in the input, no including the header.
`fileEncoding` | The name of the encoding to be assumed. Only used when `con` is a character string naming a file.
`colClasses` | an optional character vector indicating the column types. A vector of classes to be assumed for the output dataframe. If it is a list, `class(x)[1]` will be used to determine the class of the contained element. It will not be recycled, and must be at least as long as the longest row if `strict` is `TRUE`. Possible values are `"NULL"` (when the column is skipped) one of the six atomic vector types (`'character'`, `'numeric'`, `'logical'`, `'integer'`, `'complex'`, `'raw'`) or `POSIXct`. 'POSIXct' will parse date format in the form "YYYY-MM-DD hh:mm:ss.sss" assuming GMT time zone. The separators between digits can be any non-digit characters and only the date part is mandatory. See also `fasttime::asPOSIXct` for details.
`nrows` | integer: the maximum number of rows to read in. Negative and other invalid values are ignored.
`nsep` | index name separator (single character) or `NA` if no index names are included
`strict` | logical, if `FALSE` then `dstrsplit` will not fail on parsing errors, otherwise input not matching the format (e.g. more columns than expected) will cause an error.
`nrowsClasses` | integer. Maximum number of rows of data to read to learn column types. Not used when `col_types` is supplied.
`quote` | the set of quoting characters as a length 1 vector. To disable quoting altogether, use `quote = ""`. Quoting is only considered for columns read as character.
`...` | additional parameters to pass to `read.csv.raw`

### Details

See `dstrsplit` for the details of `nsep`, `sep`, and `strict`.

### Value

A data frame containing a representation of the data in the file.

### Author(s)

Taylor Arnold and Simon Urbanek

[Package iotools version 0.2-5 Index]