Replace multiple letters with accents with gsub

Question

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.

If you wanted to replace different patterns with the same thing, it should be possible with `lapply`, but as you want to replace different patterns with different strings, I think you will still have to specified these one way or another... — juba, Mar 06 '13 at 17:33
The `gsubfn` function in the `gsubfn` package is a generalization of `gsub` that can do that in one call: `gsubfn(".", list("á"="a", "é"="e", "ó"="o"), c("á","é","ó"))` — G. Grothendieck, Mar 06 '13 at 20:39
@G.Grothendieck. Thats great and also working for all type of characters. Very valuable comment. Thank you! — Joschi, Mar 07 '13 at 10:16
For people searching for a more general solution to this question, here is a more helpful answer: http://stackoverflow.com/a/7664655/1036500 — Ben, Jun 26 '14 at 13:33
@G.Grothendieck would you also post this as an answer so that future visitors see it as such? — Sam Firke, May 09 '15 at 14:33

score 84 · Accepted Answer · answered Mar 06 '13 at 17:41

84

Use the character translation function

chartr("áéó", "aeo", mydata)

answered Mar 06 '13 at 17:41

kith

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Thats cool for characters... But does this also work with special characaters e.g. underscores, points, etc... It's not within the question, still would be interesting to know something for this case too... – Joschi Mar 06 '13 at 17:49
@Joschi, your question doesn't talk about it. I think you'll have to escape them because they are special characters... – Arun Mar 06 '13 at 18:55

score 33 · Answer 2 · answered Mar 06 '13 at 17:40

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"

score 28 · Answer 3 · answered Mar 06 '13 at 19:49

28

Maybe this can be usefull:

iconv('áéóÁÉÓçã', to="ASCII//TRANSLIT")
[1] "aeoAEOca"

answered Mar 06 '13 at 19:49

Rcoster

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On the most current version of R that I'm using the call `iconv('áéóÁÉÓçã', to="ASCII//TRANSLIT")` returns `"'a'e'o'A'E'Oc~a"`. Did the behavior change across R versions, or does this have to do with my default encoding? – aaron Jul 12 '16 at 14:55
@Aaron: Don't know if is an encoding problem. I tried here at R 3.3.1 and worked as expected. – Rcoster Jul 13 '16 at 17:45

score 19 · Answer 4 · answered Jul 03 '16 at 15:51

19

You can use stringi package to replace these characters.

> stri_trans_general(c("á","é","ó"), "latin-ascii")

[1] "a" "e" "o"

answered Jul 03 '16 at 15:51

Maciej

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score 11 · Answer 5 · answered Oct 30 '16 at 16:16

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"

score 7 · Answer 6 · answered Mar 06 '13 at 17:51

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) 
}

score 7 · Answer 7 · answered May 26 '16 at 14:03

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)

score 3 · Answer 8 · answered Mar 06 '13 at 17:44

3

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"

answered Mar 06 '13 at 17:44

Jilber Urbina

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score 3 · Answer 9 · answered Mar 12 '17 at 04:57

3

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.

answered Mar 12 '17 at 04:57

Dthal

3,216
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score 1 · Answer 10 · answered Feb 21 '17 at 23:48

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)]

Maria · Answer 11 · 2022-06-10T12:32:00.663

0

You can also combine them with gsub:

mydata <- gsub("á","a", gsub("é","e", gsub("í","i", gsub("ó","o", gsub ("ú", "u", mydata)))))

edited Jun 10 '22 at 12:32

answered Jan 25 '19 at 14:00

Maria

169
1
4

Replace multiple letters with accents with gsub

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