Simple script that count the number of occurrences of a word in a string (from Programming Ruby 1.9)

word_frequency.rb

# word_frequency.rb
#
# simple script that count the number of occurrences of a word in a string
#
#

def word_from_string(string)
	#scan return an array of substring matching a given pattern
	string.downcase.scan(/[\w']+/)
end

def count_frequency(word_list)
	counts = Hash.new(0)
	for word in word_list
		counts[word] += 1
	end
	counts
end

raw_text = File.read("para.txt")
word_list = word_from_string(raw_text)
counts = count_frequency(word_list)
sorted = counts.sort_by {|word, count| count }

top_5 = sorted.last(5)

puts "\nTop 5"
# ugly - too intimate with the array. It knows its size and its structure
for i in 0...5
	word = top_5[i][0]
	count = top_5[i][1]

	puts "#{word}: #{count}"
end

puts "\nTop 5"
# better - uses iterator and blocks to achieve the same result
top_5.each do |word, count|
	puts "#{word}: #{count}"
end

puts "\nTop 5"
# better - using map to invoke an operation on each array's element
top_5.map { |word, count| puts "#{word}: #{count}" }