How do I remove emoji from string

Question

My problem is to remove emoji from a string, but not CJK (Chinese, Japanese, Korean) characters from a string using regex. I tried to use this regex:

REGEX = /[^\u1F600-\u1F6FF\s]/i

This regex works fine except it also detects the Chinese, Japanese and Korean character where I need those characters. Any idea how to solve this issue?

Answer 1

Karol S already provided a solution, but the reason might not be clear:

"\u1F600" is actually "\u1F60" followed by "0":

"\u1F60"    # => "ὠ"
"\u1F600"   # => "ὠ0"

You have to use curly braces for code points above FFFF:

"\u{1F600}" #=> "😀"

Therefore the character class [\u1F600-\u1F6FF] is interpreted as [\u1F60 0-\u1F6F F], i.e. it matches "\u1F60", the range "0".."\u1F6F" and "F".

Using curly braces solves the issue:

/[\u{1F600}-\u{1F6FF}]/

This matches (emoji) characters in these unicode blocks:

• U+1F600..U+1F64F Emoticons
• U+1F650..U+1F67F Ornamental Dingbats
• U+1F680..U+1F6FF Transport and Map Symbols

---

You can also use unpack, pack, and between? to achieve a similar result. This also works for Ruby 1.8.7 which doesn't support Unicode in regular expressions.

s = 'Hi!😀'
#=> "Hi!\360\237\230\200"

s.unpack('U*').reject{ |e| e.between?(0x1F600, 0x1F6FF) }.pack('U*')
#=> "Hi!" 

---

Regarding your Rubular example – Emoji are single characters:

"😀".length  #=> 1
"😀".chars   #=> ["😀"]

Whereas kaomoji are a combination of multiple characters:

"^_^".length #=> 3
"^_^".chars  #=> ["^", "_", "^"]

Matching these is a very different task (and you should ask that in a separate question).

Answer 2

I am using one based on this script.

 def strip_emoji(text)
    text = text.force_encoding('utf-8').encode
    clean = ""

    # symbols & pics
    regex = /[\u{1f300}-\u{1f5ff}]/
    clean = text.gsub regex, ""

    # enclosed chars 
    regex = /[\u{2500}-\u{2BEF}]/ # I changed this to exclude chinese char
    clean = clean.gsub regex, ""

    # emoticons
    regex = /[\u{1f600}-\u{1f64f}]/
    clean = clean.gsub regex, ""

    #dingbats
    regex = /[\u{2702}-\u{27b0}]/
    clean = clean.gsub regex, ""
  end

Results:

irb> strip_emoji("👽😀☂❤华み원❤")
=> "华み원"