Extract Function Generator
In qdapRegex: Regular Expression Removal, Extraction, and Replacement Tools

View source: R/rm_.R

rm_	R Documentation

Remove/Replace/Extract Function Generator

Description

Remove/replace/extract substrings from a string. A function generator used to make regex functions that operate typical of other qdapRegex rm_XXX functions. Use rm_ for removal and ex_ for extraction.

Usage

rm_(...)

ex_(...)

Arguments

...

Arguments passed to rm_default. Generally, pattern and extract are the most useful parameters to change. Arguments that can be set include:

text.var: The text variable.
trim: logical. If TRUE removes leading and trailing white spaces.
clean: logical. If TRUE extra white spaces and escaped character will be removed.
pattern: A character string containing a regular expression (or character string for fixed = TRUE) to be matched in the given character vector.
replacement: Replacement for matched pattern.
extract: logical. If TRUE strings are extracted into a list of vectors.
dictionary: A dictionary of canned regular expressions to search within if pattern begins with "@rm_".
...: Other arguments passed to gsub.

Value

Returns a function that operates typical of other qdapRegex rm_XXX functions but with user defined defaults.

Examples

rm_digit <- rm_(pattern="[0-9]")
rm_digit("  I 12 li34ke ice56cream78.  ")

rm_lead <- rm_(pattern="^\\s+", trim = FALSE, clean = FALSE)
rm_lead("  I 12 li34ke ice56cream78.    ")

rm_all_except_letters <- rm_(pattern="[^ a-zA-Z]")
rm_all_except_letters("  I 12 li34ke ice56cream78.    ")

extract_consec_num <- rm_(pattern="[0-9]+", extract = TRUE)
extract_consec_num("  I 12 li34ke ice56cream78.  ")

## Using the supplemental dictionary dataset:
x <- "A man lives there!  The dog likes it. I want the map. I want an apple."

extract_word_after_the <- rm_(extract=TRUE, pattern="@after_the")
extract_word_after_a <- rm_(extract=TRUE, pattern="@after_a")
extract_word_after_the(x)
extract_word_after_a(x)

f <- rm_(pattern="@time_12_hours")
f("I will go at 12:35 pm")

x <- c(
    "test@aol.fg.com",
    "test@hotmail.com",
    "test@xyzrr.lk.edu",
    "test@abc.xx.zz.vv.net"
)

file_ext2 <- rm_(pattern="(?<=\\.)[a-z]*$", extract=TRUE)
tools::file_ext(x)
file_ext2(x)

qdapRegex documentation built on Oct. 17, 2023, 5:06 p.m.