| Title: | Memory-Map Character Files |
| Version: | 0.3.0 |
| Date: | 2019-02-26 |
| Description: | Uses memory-mapping to enable the random access of elements of a text file of characters separated by characters as if it were a simple R(cpp) matrix. |
| Encoding: | UTF-8 |
| License: | GPL-3 |
| LazyData: | TRUE |
| ByteCompile: | TRUE |
| Depends: | R (≥ 3.3.0) |
| Imports: | methods, Rcpp |
| LinkingTo: | Rcpp, rmio |
| Suggests: | covr, testthat |
| RoxygenNote: | 6.1.0.9000 |
| URL: | https://github.com/privefl/mmapcharr |
| BugReports: | https://github.com/privefl/mmapcharr/issues |
| Collate: | 'RcppExports.R' 'extract.R' 'file-dim.R' 'mmapchar.R' 'mmapcharr-package.r' 'utils.R' |
| NeedsCompilation: | yes |
| Packaged: | 2019-02-26 09:09:38 UTC; privef |
| Author: | Florian Privé [aut, cre] |
| Maintainer: | Florian Privé <florian.prive.21@gmail.com> |
| Repository: | CRAN |
| Date/Publication: | 2019-02-26 12:20:02 UTC |
mmapcharr.
Description
mmapcharr.
Create an Implementation of [ For Custom Matrix-Like Types
Description
extract is a function that converts different index types such as negative
integer vectors or logical vectors passed to the [ function as i
(e.g. X[i]) or i and j (e.g. X[i, j]) into positive
integer vectors. The converted indices are provided as the i parameter of
extract_vector or i and j parameters of extract_matrix to facilitate
implementing the extraction mechanism for custom matrix-like types.
Usage
Extract(extract_vector, extract_matrix)
Arguments
extract_vector |
A function in the form of |
extract_matrix |
A function in the form of |
Details
The custom type must implement methods for dim for this function
to work. Implementing methods for nrow and ncol is not necessary
as the default method of those generics calls dim internally.
This idea initially comes from package crochet.
Value
A function in the form of function(x, i, j, ..., drop = TRUE) that
is meant to be used as a method for [ for a custom type.
File dimensions
Description
Number of lines and columns of file (and extra 'return' characters).
Usage
dim_file(file)
Arguments
file |
Path to file. |
Value
The number of lines and columns of file (and extra 'return' characters).
Examples
tmpfile <- tempfile()
write(0:9, tmpfile, ncolumns = 2)
dim_file(tmpfile)
Class mmapchar
Description
A reference class for storing and accessing matrix-like data stored on disk in files containing only characters (digits) separated by a character.
Usage
mmapchar(file, code)
Arguments
file |
Path of the file. |
code |
Integer vector of size 256 to access integers instead of
|
Examples
test_file <- system.file("testdata/test-windows.txt", package = "mmapcharr")
test <- mmapchar(test_file, code = mmapcharr:::CODE_012)
test[, 1:3]
test[]
readLines(test_file)
Methods for the mmapchar class
Description
Methods for the mmapchar class
Accessor methods for class mmapchar. You can use positive and negative indices,
logical indices (that are recycled) and also a matrix of indices (but only
positive ones).
Dimension and type methods for class mmapchar.
Usage
## S4 method for signature 'mmapchar'
x[i, j, ..., drop = TRUE]
## S4 method for signature 'mmapchar'
dim(x)
## S4 method for signature 'mmapchar'
length(x)
Arguments
x |
A mmapchar object. |
i |
A vector of indices (or nothing). You can use positive and negative indices, logical indices (that are recycled) and also a matrix of indices (but only positive ones). |
j |
A vector of indices (or nothing). You can use positive and negative indices, logical indices (that are recycled). |
... |
Not used. Just to make nargs works. |
drop |
Whether to delete the dimensions of a matrix which have one dimension equals to 1. |
Size of line
Description
Number of elements of each line of a file.
Usage
nelem(file)
Arguments
file |
Path to file. |
Value
The number of elements of each line of a file.
Examples
tmpfile <- tempfile()
write(1:10, tmpfile, ncolumns = 2)
nline(tmpfile)
Number of lines
Description
Number of lines of a file.
Usage
nline(file)
Arguments
file |
Path to file. |
Value
The number of lines of the file.
Examples
tmpfile <- tempfile()
write(1:5, tmpfile, ncolumns = 1)
nline(tmpfile)