extract: Extract a Parenthetically-grouped Substring of a Regular...

In metrumrg: Pharmacometric Tools for Data Preparation, Modeling, Simulation, and Reporting

Description

Given a regular expression with parenthetically-grouped substrings, return or drop the substring of interest.

Usage

extract(x, pattern, group = 0, invert = FALSE, ...)

Arguments

x	character
pattern	passed to regexec
group	one less than the index used by regexec
invert	drop the matched text, returning everything else
...	ignored

Details

regexec determines all the numbered matches corresponding to sets of parentheses. extract uses these to locate and return particular numbered matches, or to delete them, returning what remains. group = 0 refers to the entire match (first element of each regexec result). Non-matches give an empty string; matching NA results in NA.

Value

character

Author(s)

Tim Bergsma

References

http://metrumrg.googlecode.com

See Also

• regexec

• guidetext

Examples

x <- c(' kg ',' //a/A//b/B// ',NA,' kg [ 4 , 8.2 ]','(,1.025e-6]','(,] ')
pattern <- '((\\(|\\[) *([-+eE.0-9]*) *, *([-+eE.0-9]*) *(\\)|\\])) *$'
extract(x,pattern,group=5)	

metrumrg documentation built on May 2, 2019, 5:55 p.m.