Portable tools for UTF-8 character data

R and character encoding

The character encoding of determines the translation of the letters, digits, or other codepoints (atomic components of a text) into a sequence of bytes. A byte sequence may translate into valid text in one character encoding, but give nonsense in other character encodings.

For historic reasons, R can store strings in different ways:

1. in the “native” encoding, the default encoding of the operating system
2. in UTF-8, the most prevalent and versatile encoding nowadays
3. in “latin1”, a popular encoding in Western Europe
4. as “bytes”, leaving the interpretation to the user

On OS X and Linux, the “native” encoding is often UTF-8, but on Windows it is not. To add to the confusion, the encoding is a property of individual strings in a character vector, and not of the entire vector.

Why UTF-8?

When working with text, it is advisable to use UTF-8, because it allows encoding virtually any text, even in foreign languages that contain symbols that cannot be represented in your system’s native encoding. The UTF-8 encoding possesses several nice technical properties, and is by far the predominant encoding on the Web. Standardization on a “universal” encoding faciliates data exchange.

Because of R’s special handling of strings, some care must be taken to make sure that you’re actually using the UTF-8 encoding. Many functions in R will hide encoding issues from you, and transparently convert to UTF-8 as necessary. However, some functions (such as reading and writing files) will stubbornly prefer the native encoding.

The enc package provides helpers for converting all textual components of an object to UTF-8, and for reading and writing files in UTF-8 (with a LF end-of-line terminator by default). It also defines an S3 class for tagging all-UTF-8 character vectors and ensuring that updates maintain the UTF-8 encoding. Examples for other packages that use UTF-8 by default are:

• readr, readxl, and haven for data input and output

• stringi and stringr for string manipulation

• testthat and roxygen2 for package development

Example

library(enc)
utf8(c("a", "ä"))
#> [1] "a" "ä"
as_utf8(1)
#> [1] "1"

a <- utf8("ä")
a[2] <- "ö"
class(a)
#> [1] "utf8"

data.frame(abc = letters[1:3], utf8 = utf8(letters[1:3]))
#>   abc utf8
#> 1   a    a
#> 2   b    b
#> 3   c    c

Install the package from GitHub:

# install.packages("devtools")
devtools::install_github("krlmlr/enc")