Working with strings

string <- 'Hello world 2016 !!'

Remove all characters from a string

gsub('\\D', '', string, fixed = FALSE)

## [1] "2016"

Multiple character substitution

chartr('wld', 'bde', string)

## [1] "Heddo borde 2016 !!"

Regular expressions

string2 <- c('blank', 'wade', 'waste', 'rubbish', 'dedekind', 'bated')

# Get all words finishing by "de" or "te"
grepl(pattern = "^.+(de|te)$", x = string2, ignore.case = FALSE)

## [1] FALSE  TRUE  TRUE FALSE FALSE FALSE

# Match either empty strings or letters
grepl("(^$)|([A-Za-z]+)", x = string2, ignore.case = FALSE)

## [1] TRUE TRUE TRUE TRUE TRUE TRUE

Note: grepl() returns logic, grep() returns numeric and grep(value = TRUE). returns the match