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.

Answer 1

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.

Answer 2

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)]

Answer 3

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"

Answer 4

Use the character translation function

chartr("áéó", "aeo", mydata)