Matching a specific code point or code groups

Things can get tricky when some characters can be specified two ways, for example è, an e with a grave accent, can be specified either with the single code point \u00e8 or the combination of a \u0065 and a combining grave accent \u0300. They look the same:

x <- c("\u00e8", "\u0065\u0300")
writeLines(x)

But, specifying the single code point only matches that version:

str_view(x, "\u00e8")

The stringi package that stringr is built on contains functions for converting between the two forms. stri_trans_nfc() composes characters with combining accents into a single character. stri_trans_nfd() decomposes character with accents into separate letter and accent characters. You can see how the characters differ by looking at the hexadecimal codes.

as.hexmode(utf8ToInt(stri_trans_nfd("\u00e8")))
as.hexmode(utf8ToInt(stri_trans_nfc("\u0065\u0300")))

In Unicode, an accent is known as a diacritic Unicode Property, and you can match it using the rebus value UP_DIACRITIC.

Vietnamese makes heavy use of diacritics to denote the tones in its words. In this exercise, you'll manipulate the diacritics in the names of Vietnamese rulers.

이 연습은 강의의 일부입니다

String Manipulation with stringr in R

강의 보기

연습 안내

Names of rulers from the 18th Century Vietnamese Tây Sơn dynasty are shown in the script.

tay_son_builtin has the accents built into each letter. Run the code that defines and prints this variable.
Call stri_trans_nfd() to decompose the letters with accents into separate letter and accent characters, and assign the result to tay_son_separate.
Print tay_son_separate to verify the names still display the same way.
View all the accents by calling str_view_all() and matching UP_DIACRITIC. The match is shown after the letter that the diacritic belongs to.

실습형 인터랙티브 연습

이 예제를 이 샘플 코드를 완성하여 풀어보세요.

# Names with builtin accents
(tay_son_builtin <- c(
  "Nguy\u1ec5n Nh\u1ea1c", 
  "Nguy\u1ec5n Hu\u1ec7",
  "Nguy\u1ec5n Quang To\u1ea3n"
))

# Convert to separate accents
tay_son_separate <- ___

# Verify that the string prints the same
tay_son_separate

# Match all accents
str_view_all(tay_son_separate, ___)

코드 편집 및 실행