str_replace()
replaces the first match; str_replace_all()
replaces
all matches.
str_replace(string, pattern, replacement)str_replace_all(string, pattern, replacement)
A character vector the same length as
string
/pattern
/replacement
.
Input vector. Either a character vector, or something coercible to one.
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.
str_replace_na()
to turn missing values into "NA";
stri_replace()
for the underlying implementation.
fruits <- c("one apple", "two pears", "three bananas")
str_replace(fruits, "[aeiou]", "-")
str_replace_all(fruits, "[aeiou]", "-")
str_replace_all(fruits, "[aeiou]", toupper)
str_replace_all(fruits, "b", NA_character_)
str_replace(fruits, "([aeiou])", "")
str_replace(fruits, "([aeiou])", "\\1\\1")
# Note that str_replace() is vectorised along text, pattern, and replacement
str_replace(fruits, "[aeiou]", c("1", "2", "3"))
str_replace(fruits, c("a", "e", "i"), "-")
# 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"))
# 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)
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