From: Joel Pearson <lists@...>
Date: 2013-01-29T03:01:27+09:00
Subject: Re: Please explain in English

I'll try to break it down, let us know if there's anything further that 
needs clarifying.

#Declare a method with one argument
  def count_words(string)

#Create an empty Hash (aka Dictionary) to modify it later
  res = Hash.new(0)

#Convert the whole string to lowercase (returns a new object, doesn't 
modify in place)
  string.downcase

#Use Regex to return each word ( "+" means until a non-word character) 
as an enumerator
  .scan(/\w+/)

#Iterate through each of the words and return (map) a new object (which 
isn't used in this case)
  .map{|word|

#Populate the hash on each iteration (overwriting existing values)
res[word] =

#Get the "size" of the array returned by searching the string for all 
instance of the current word
  string.downcase.scan(/\b#{word}\b/).size}

#Explicitly return the hash ("return" isn't strictly required as this is 
the last line)
  return res
end


I can't helping feeling that there is a more efficient way to do this, 
given that the loop iterates needlessly multiple times over the 
duplicates.

This does the same thing (not sure whether it's faster):

def count_words(string)
  res = {}
  string.downcase!
  string.scan( /\w+/ ).uniq.each{ |word| res[word] =
    string.scan(/\b#{word}\b/).size }
  res
end

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