Is there a nice way to check if a string contains at least one string from an array of strings?

Question

string.include?(other_string) is used to check if a string contains another string. Is there a nice way to check if a string contains at least one string from an array of strings?

string_1 = "a monkey is an animal. dogs are fun"

arrays_of_strings_to_check_against = ['banana', 'fruit', 'animal', 'dog']

This would return true, because string_1 contains the string 'animal'. If we remove 'animal' from arrays_of_strings_to_check_against, it would return false.

Note that the string 'dog' from arrays_of_strings_to_check_against should not match 'dogs' from string_1, because it has to be a complete match.

I'm using Rails 3.2.0 and Ruby 1.9.2

Answer 1

arrays_of_strings_to_check_against.map{ |o| string_1 =~ /\b#{Regexp.escape(o)}\b/ }.any?

Or even:

arrays_of_strings_to_check_against.any?{ |o| string_1 =~ /\b#{Regexp.escape(o)}\b/ }

Answer 2

str1  = "a monkey is an animal. dogs are fun"
str2  = "a monkey is a primate. dogs are fun"
words = %w[banana fruit animal dog]
word_test = /\b(?:#{ words.map{|w| Regexp.escape(w) }.join("|") })\b/i

p str1 =~ word_test,  #=> 15
  str2 =~ word_test   #=> nil

If you get nil there was no match; otherwise you'll get an integer (which you can treat just like true) that is the index of the offset where the match occurred.

If you absolutely must have true or false, you can do:

any_match = !!(str =~ word_test)

The regular expression created by interpolation is:

/\b(?:banana|fruit|animal|dog)\b/i

…where the \b matches a "word boundary", thus preventing dog from matching in dogs.

Edit: The answer above no longer uses Regexp.union since that creates a case-sensitive regex, while the question requires case-insensitive.

Alternatively, we can force everything to lowercase before the test to gain case-insensitivity:

words = %w[baNanA Fruit ANIMAL dog]
word_test = /\b#{ Regexp.union(words.map(&:downcase)) }\b/
p str1.downcase =~ word_test,
  str2.downcase =~ word_test

Answer 3

If array_of_strings_to_check_against contains only whole words, and not multi-word strings, you can & the two arrays together. If the result has length > 0, there was a match. Prior to .split(' '), however, you must remove non-word, non-space characters. Otherwise, in this case it would fail because animal. (with .) isn't in your array.

if (string_1.gsub(/[^\w\s]/).split(' ') & array_of_strings_to_check_against).length > 0
  puts "Match!!"
end

Update after comments: case-insensitive version

if (string_1.downcase.gsub(/[^\w\s]/).split(' ') & array_of_strings_to_check_against).length > 0
  puts "Match!!"
end