tangleR {relax} | R Documentation

## function to tangle a file

### Description

`tangleR` reads a file that is written according to the rules of the `noweb` system and performs a specific kind of tangling. As a result a `.R`-file is generated.

### Usage

    tangleR(in.file, out.file, expand.roots = NULL,
    expand.root.start = TRUE)

### Arguments

`in.file` | name of input file
`out.file` | name of output file; if missing the extension of the input file is turned to `.R`
`expand.roots` | name(s) of root(s) to be expanded; if NULL all will be processed
`expand.root.start` | if TRUE (default) root chunk "start" will be expanded

### Details

General remarks: A `noweb` file consists of a mixture of text and code chunks. An `@` character (in column 1 of a line) indicates the beginning of a text chunk. `<<name of code chunk>>=` (starting at column 1 of a line) is a header line of a code chunk with a name defined by the text between `<<` and `>>=`. A code chunk is finished by the beginning of the next text chunk. Within the code chunk you can use other code chunks by referencing them by name ( for example by: `<<name of code chunk>>` ). In this way you can separate a big job in smaller ones.

Special remarks: `tangleR` expands code chunk `start` if flag `expand.root.start` is TRUE. Code chunks will be surrounded by comment lines showing the number of the code chunk the code is coming from. If you want to use `<<` or `>>` in your code it may be necessary to escape them by an `@`-sign. Then you have to type in: `@<<` or `@>>`.

### Value

usually a file with R code is generated

### Author(s)

Hans Peter Wolf

### References

http://www.eecs.harvard.edu/~nr/noweb/intro.html

### See Also

`weaveR`

### Examples

    ## Not run:
    ## This example cannot be run by examples() but should be work in an interactive R session
      tangleR("testfile.rev")
    ## End(Not run)
    "tangleR(\"testfile.rev\")"
    ## The function is currently defined as
    function(in.file,out.file,expand.roots=NULL,expand.root.start=TRUE){
    # german documentation of the code:
    # look for file webR.pdf, P. Wolf 050204
    ...
      }

[Package relax version 1.01 Index]