Pattern to look for.
The default interpretation is a regular expression, as described
in
stringi::about_search_regex
. Control options with
regex()
.
For
str_replace_all()
this can also be a named vector
(
c(pattern1 = replacement1)
), in order to perform multiple replacements
in each element of
string
.
Match a fixed string (i.e. by comparing only bytes), using
fixed()
. This is fast, but approximate. Generally,
for matching human text, you'll want
coll()
which
respects character matching rules for the specified locale.
The replacement value, usually a single string,
but it can be the a vector the same length as
string
or
pattern
.
References of the form
\1
,
\2
, etc will be replaced with
the contents of the respective matched group (created by
()
).
Alternatively, supply a function, which will be called once for each
match (from right to left) and its return value will be used to replace
the match.
fruits <- c("one apple", "two pears", "three bananas")
str_replace(fruits, "[aeiou]", "-")
#> [1] "-ne apple" "tw- pears" "thr-e bananas"
str_replace_all(fruits, "[aeiou]", "-")
#> [1] "-n- -ppl-" "tw- p--rs" "thr-- b-n-n-s"
str_replace_all(fruits, "[aeiou]", toupper)
#> [1] "OnE ApplE" "twO pEArs" "thrEE bAnAnAs"
str_replace_all(fruits, "b", NA_character_)
#> [1] "one apple" "two pears" NA
str_replace(fruits, "([aeiou])", "")
#> [1] "ne apple" "tw pears" "thre bananas"
str_replace(fruits, "([aeiou])", "\\1\\1")
#> [1] "oone apple" "twoo pears" "threee bananas"
# Note that str_replace() is vectorised along text, pattern, and replacement
str_replace(fruits, "[aeiou]", c("1", "2", "3"))
#> [1] "1ne apple" "tw2 pears" "thr3e bananas"
str_replace(fruits, c("a", "e", "i"), "-")
#> [1] "one -pple" "two p-ars" "three bananas"
# If you want to apply multiple patterns and replacements to the same
# string, pass a named vector to pattern.
fruits %>%
str_c(collapse = "---") %>%
str_replace_all(c("one" = "1", "two" = "2", "three" = "3"))
#> [1] "1 apple---2 pears---3 bananas"
# Use a function for more sophisticated replacement. This example
# replaces colour names with their hex values.
colours <- str_c("\\b", colors(), "\\b", collapse="|")
col2hex <- function(col) {
rgb <- col2rgb(col)
rgb(rgb["red", ], rgb["green", ], rgb["blue", ], max = 255)
x <- c(
"Roses are red, violets are blue",
"My favourite colour is green"
str_replace_all(x, colours, col2hex)
#> [1] "Roses are #FF0000, violets are #0000FF"
#> [2] "My favourite colour is #00FF00"
