R: Visualize Regular Expressions

explain {qdapRegex}

R Documentation

Visualize Regular Expressions

Description

Visualize regular expressions using http://www.regexper.com & http://rick.measham.id.au/paste/explain.

Usage

explain(pattern, open = FALSE, print = TRUE,
  dictionary = getOption("regex.library"))

Arguments

`pattern`	A character string containing a regular expression or a character string starting with `"@"` that is a regular expression from a qdapRegex dictionary.
`open`	logical. If `TRUE` the default browser will attempt to open http://www.regexper.com page. Setting `open = 2` will utilize an unstable visualization via https://www.debuggex.com. This approach utilizes a non-api scrape that is subject to change and not guaranteed to be stable. The regex is set to Python flavor which handles lookbehinds that the Java based http://www.regexper.com does not. This functionality was developed by Matthew Flickinger (see http://stackoverflow.com/a/27574103/1000343 for details). Note that the user must have httr installed or will be prompted if the package cannot be `require`d.
`print`	logical. Should `explain` print output to the console?
`dictionary`	A dictionary of canned regular expressions to search within.

Details

Note that http://www.regexper.com is a Java based regular expression viewer. Lookbehind and negative lookbehinds are not respected.

Value

Prints http://rick.measham.id.au/paste/explain to the console, attempts to open the url to the visual representation provided by http://www.regexper.com, and invisibly returns a list with the URLs.

Author(s)

Ananda Mahto, Matthew Flickinger, and Tyler Rinker <tyler.rinker@gmail.com>.

References

http://stackoverflow.com/a/27489977/1000343
http://www.regexper.com
http://rick.measham.id.au/paste/explain
http://stackoverflow.com/a/27574103/1000343

Examples

explain("\\s*foo[A-Z]\\d{2,3}")
explain("@rm_time")
## Not run: 
explain("\\s*foo[A-Z]\\d{2,3}", open = TRUE)
explain("@rm_time", open = TRUE)

## End(Not run)

[Package qdapRegex version 0.7.2 Index]