Append strings to array if found in paragraph using `.match` in Ruby - arrays

Question

I'm attempting to search a paragraph for each word in an array, and then output a new array with only the words that could be found.
But I've been unable to get the desired output format so far.
paragraph = "Japan is a stratovolcanic archipelago of 6,852 islands.
The four largest are Honshu, Hokkaido, Kyushu and Shikoku, which make up about ninety-seven percent of Japan's land area.
The country is divided into 47 prefectures in eight regions."
words_to_find = %w[ Japan archipelago fishing country ]
words_found = []
words_to_find.each do |w|
paragraph.match(/#{w}/) ? words_found << w : nil
end
puts words_found
Currently the output I'm getting is a vertical list of printed words.
Japan
archipelago
country
But I would like something like, ['Japan', 'archipelago', 'country'].
I don't have much experience matching text in a paragraph and am not sure what I'm doing wrong here. Could anyone give some guidance?

Answer 1

this is because you are using puts to print the elements of the array . appending "\n" to the end of every element "word":
#!/usr/bin/env ruby
def run_me
paragraph = "Japan is a stratovolcanic archipelago of 6,852 islands.
the four largest are Honshu, Hokkaido, Kyushu and Shikoku, which make up about ninety-seven percent of Japan's land area.
the country is divided into 47 prefectures in eight regions."
words_to_find = %w[ Japan archipelago fishing country ]
find_words_from_a_text_file paragraph , words_to_find
end
def find_words_from_a_text_file( paragraph , *words_to_find )
words_found = []
words_to_find.each do |w|
paragraph.match(/#{w}/) ? words_found << w : nil
end
# print array with enum .
words_found.each { |x| puts "with enum and puts : : #{x}" }
# or just use "print , which does not add anew line"
print "with print :"; print words_found "\n"
# or with p
p words_found
end
run_me
outputs :
za:ruby_dir za$ ./fooscript.rb
with enum and puts : : ["Japan", "archipelago", "fishing", "country"]
with print :[["Japan", "archipelago", "fishing", "country"]]

Answer 2

Here are a couple of ways to do that. Both are case-indifferent.
Use a regular expression
r = /
\b # Match a word break
#{ Regexp.union(words_to_find) } # Match any word in words_to_find
\b # Match a word break
/xi # Free-spacing regex definition mode (x)
# and case-indifferent (i)
#=> /
# \b # Match a word break
# (?-mix:Japan|archipelago|fishing|country) # Match any word in words_to_find
# \b # Match a word break
# /ix # Free-spacing regex definition mode (x)
# and case-indifferent (i)
paragraph.scan(r).uniq(&:itself)
#=> ["Japan", "archipelago", "country"]
Intersect two arrays
words_to_find_hash = words_to_find.each_with_object({}) { |w,h| h[w.downcase] = w }
#=> {"japan"=>"Japan", "archipelago"=>"archipelago", "fishing"=>"fishing",
"country"=>"country"}
words_to_find_hash.values_at(*paragraph.delete(".;:,?'").
downcase.
split.
uniq & words_to_find_hash.keys)
#=> ["Japan", "archipelago", "country"]