Can R read html-encoded emoji characters?

Question

Question

My question, explained below, is:

How can R be used to read a string that includes HTML emoji codes like ��

Answer 1

I've implemented the algorithm described by rensa above in R, and am sharing it here. I am happy to release the code snippet below under a CC0 dedication (i.e., putting this implementation into the public domain for free reuse).

This is a quick and unpolished implementation of rensa's algorithm, but it works!

utf16_double_dec_code_to_utf8 <- function(utf16_decimal_code){
  string_elements <- str_match_all(utf16_decimal_code, "&#(.*?);")[[1]][,2]

  string3a <- string_elements[1]
  string3b <- string_elements[2]

  string4a <- sprintf("0x0%x", as.numeric(string3a))
  string4b <- sprintf("0x0%x", as.numeric(string3b))

  string5a <- paste0(
    # "0x", 
    as.hexmode(string4a) - 0xd800
  )
  string5b <- paste0(
    # "0x",
    as.hexmode(string4b) - 0xdc00
  )

  string6 <- paste0(
    stringi::stri_pad(
      paste0(BMS::hex2bin(string5a), collapse = ""),
      10,
      pad = "0"
    ) %>%
      stringr::str_trunc(10, side = "left", ellipsis = ""),
    stringi::stri_pad(
      paste0(BMS::hex2bin(string5b), collapse = ""),
      10,
      pad = "0"
    ) %>%
      stringr::str_trunc(10, side = "left", ellipsis = "")
  )

  string7 <- BMS::bin2hex(as.numeric(strsplit(string6, split = "")[[1]]))

  string8 <- as.hexmode(string7) + 0x10000

  unicode_pattern <- string8
  unicode_pattern
}

make_unicode_entity <- function(x) {
  paste0("\\U000", utf16_double_dec_code_to_utf8(x))
}
make_html_entity <- function(x) {
  paste0("&#x", utf16_double_dec_code_to_utf8(x), ";")
}

# An example string, using the "hug" emoji:
example_string <- "test �� test"

output_string <- stringr::str_replace_all(
  example_string,
  "(&#[0-9]*?;){2}",  # Find all two-character "&#...;&#...;" codes.
  make_unicode_entity
  # make_html_entity
)

cat(output_string)

# To print Unicode string (doesn't display in R console, but can be copied and
# pasted elsewhere:
# (This assumes you've used 'make_unicode_entity' above in the str_replace_all
# call):
stringi::stri_unescape_unicode(output_string)