Replace multiple letters with accents with gsub
RRegexGsubR Problem Overview
of course I could replace specific arguments like this:
mydata=c("á","é","ó")
mydata=gsub("á","a",mydata)
mydata=gsub("é","e",mydata)
mydata=gsub("ó","o",mydata)
mydata
but surely there is a easier way to do this all in onle line, right? I dont find the gsub help to be very comprehensive on this.
R Solutions
Solution 1 - R
Use the character translation function
chartr("áéó", "aeo", mydata)
Solution 2 - R
An interesting question! I think the simplest option is to devise a special function, something like a "multi" gsub():
mgsub <- function(pattern, replacement, x, ...) {
if (length(pattern)!=length(replacement)) {
stop("pattern and replacement do not have the same length.")
}
result <- x
for (i in 1:length(pattern)) {
result <- gsub(pattern[i], replacement[i], result, ...)
}
result
}
Which gives me:
> mydata <- c("á","é","ó")
> mgsub(c("á","é","ó"), c("a","e","o"), mydata)
[1] "a" "e" "o"
Solution 3 - R
Maybe this can be usefull:
iconv('áéóÁÉÓçã', to="ASCII//TRANSLIT")
[1] "aeoAEOca"
Solution 4 - R
You can use stringi
package to replace these characters.
> stri_trans_general(c("á","é","ó"), "latin-ascii")
[1] "a" "e" "o"
Solution 5 - R
This is very similar to @kith, but in function form, and with the most common diacritcs cases:
removeDiscritics <- function(string) {
chartr(
"ŠŽšžŸÀÁÂÃÄÅÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖÙÚÛÜÝàáâãäåçèéêëìíîïðñòóôõöùúûüýÿ"
,"SZszYAAAAAACEEEEIIIIDNOOOOOUUUUYaaaaaaceeeeiiiidnooooouuuuyy"
, string
)
}
removeDiscritics("test áéíóú")
> "test aeiou"
Solution 6 - R
Another mgsub
implementation using Reduce
mystring = 'This is good'
myrepl = list(c('o', 'a'), c('i', 'n'))
mgsub2 <- function(myrepl, mystring){
gsub2 <- function(l, x){
do.call('gsub', list(x = x, pattern = l[1], replacement = l[2]))
}
Reduce(gsub2, myrepl, init = mystring, right = T)
}
Solution 7 - R
A problem with some of the implementations above (e.g., Theodore Lytras's) is that if the patterns are multiple characters, they may conflict in the case that one pattern is a substring of another. A way to solve this is to create a copy of the object and perform the pattern replacement in that copy. This is implemented in my package bayesbio, available on CRAN.
mgsub <- function(pattern, replacement, x, ...) {
n = length(pattern)
if (n != length(replacement)) {
stop("pattern and replacement do not have the same length.")
}
result = x
for (i in 1:n) {
result[grep(pattern[i], x, ...)] = replacement[i]
}
return(result)
}
Here is a test case:
asdf = c(4, 0, 1, 1, 3, 0, 2, 0, 1, 1)
res = mgsub(c("0", "1", "2"), c("10", "11", "12"), asdf)
Solution 8 - R
Not so elegant, but it works and does what you want
> diag(sapply(1:length(mydata), function(i, x, y) {
+ gsub(x[i],y[i], x=x)
+ }, x=mydata, y=c('a', 'b', 'c')))
[1] "a" "b" "c"
Solution 9 - R
Related to Justin's answer:
> m <- c("á"="a", "é"="e", "ó"="o")
> m[mydata]
á é ó
"a" "e" "o"
And you can get rid of the names with names(*) <- NULL
if you want.
Solution 10 - R
You can use the match
function. Here match(x, y)
returns the index of y
where the element of x
is matched. Then you can use the returned indices, to subset another vector (say z
) that contains the replacements for the values of x
, appropriately matched with y
. In your case:
mydata <- c("á","é","ó")
desired <- c('a', 'e', 'o')
desired[match(mydata, mydata)]
In a simpler example, consider the situation below, where I was trying to substitute a
for 'alpha'
, 'b'
for 'beta'
and so forth.
x <- c('a', 'a', 'b', 'c', 'b', 'c', 'e', 'e', 'd')
y <- c('a', 'b', 'c', 'd', 'e')
z <- c('alpha', 'beta', 'gamma', 'delta', 'epsilon')
z[match(x, y)]
Solution 11 - R
In this case, doesn't have so much sense, but if they are just two, you can also combine them with gsub:
mydata <- gsub("á","a", gsub("é","e",mydata))