| chartr | R Documentation |
Translate characters in character vectors, in particular from upper to lower case or vice versa.
chartr(old, new, x) tolower(x) toupper(x) casefold(x, upper = FALSE)
x |
a character vector, or an object that can be coerced to
character by |
old |
a character string specifying the characters to be translated. If a character vector of length 2 or more is supplied, the first element is used with a warning. |
new |
a character string specifying the translations. If a character vector of length 2 or more is supplied, the first element is used with a warning. |
upper |
logical: translate to upper or lower case?. |
chartr translates each character in x that is specified
in old to the corresponding character specified in new.
Ranges are supported in the specifications, but character classes and
repeated characters are not. If old contains more characters
than new, an error is signaled; if it contains fewer characters, the
extra characters at the end of new are ignored.
tolower and toupper convert upper-case characters in a
character vector to lower-case, or vice versa. Non-alphabetic
characters are left unchanged. More than one character can be mapped
to a single upper-case character.
casefold is a wrapper for tolower and toupper
provided for compatibility with S-PLUS.
A character vector of the same length and with the same attributes as
x (after possible coercion).
Elements of the result will be have the encoding declared as that of
the current locale (see Encoding) if the corresponding
input had a declared encoding and the current locale is either Latin-1
or UTF-8. The result will be in the current locale's encoding unless
the corresponding input was in UTF-8 or Latin-1, when it will be in UTF-8.
These functions are platform-dependent, usually using OS services. The latter can be quite deficient, for example only covering ASCII characters in 8-bit locales. The definition of ‘alphabetic’ is platform-dependent and liable to change over time as most platforms are based on the frequently-updated Unicode tables.
sub and gsub for other
substitutions in strings.
x <- "MiXeD cAsE 123"
chartr("iXs", "why", x)
chartr("a-cX", "D-Fw", x)
tolower(x)
toupper(x)
## "Mixed Case" Capitalizing - toupper( every first letter of a word ) :
.simpleCap <- function(x) {
s <- strsplit(x, " ")[[1]]
paste(toupper(substring(s, 1, 1)), substring(s, 2),
sep = "", collapse = " ")
}
.simpleCap("the quick red fox jumps over the lazy brown dog")
## -> [1] "The Quick Red Fox Jumps Over The Lazy Brown Dog"
## and the better, more sophisticated version:
capwords <- function(s, strict = FALSE) {
cap <- function(s) paste(toupper(substring(s, 1, 1)),
{s <- substring(s, 2); if(strict) tolower(s) else s},
sep = "", collapse = " " )
sapply(strsplit(s, split = " "), cap, USE.NAMES = !is.null(names(s)))
}
capwords(c("using AIC for model selection"))
## -> [1] "Using AIC For Model Selection"
capwords(c("using AIC", "for MODEL selection"), strict = TRUE)
## -> [1] "Using Aic" "For Model Selection"
## ^^^ ^^^^^
## 'bad' 'good'
## -- Very simple insecure crypto --
rot <- function(ch, k = 13) {
p0 <- function(...) paste(c(...), collapse = "")
A <- c(letters, LETTERS, " '")
I <- seq_len(k); chartr(p0(A), p0(c(A[-I], A[I])), ch)
}
pw <- "my secret pass phrase"
(crypw <- rot(pw, 13)) #-> you can send this off
## now ``decrypt'' :
rot(crypw, 54 - 13) # -> the original:
stopifnot(identical(pw, rot(crypw, 54 - 13)))
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