article.txt

Computer science is the study of the theory, experimentation, and engineering that form the basis for the design and use of computers. It is the scientific and practical approach to computation and its applications and the systematic study of the feasibility, structure, expression, and mechanization of the methodical procedures (or algorithms) that underlie the acquisition, representation, processing, storage, communication of, and access to, information. An alternate, more succinct definition of computer science is the study of automating algorithmic processes that scale. A computer scientist specializes in the theory of computation and the design of computational systems.[1]

Its fields can be divided into a variety of theoretical and practical disciplines. Some fields, such as computational complexity theory (which explores the fundamental properties of computational and intractable problems), are highly abstract, while fields such as computer graphics emphasize real-world visual applications. Other fields still focus on challenges in implementing computation. For example, programming language theory considers various approaches to the description of computation, while the study of computer programming itself investigates various aspects of the use of programming language and complex systems. Human–computer interaction considers the challenges in making computers and computations useful, usable, and universally accessible to humans.

frequencies.rb

# create a method 'frequencies' that takes one string as an argument => 'text'
def frequencies(text)
  # 1.) split text into an array of words
  words = text.split
  # 2.) define an empty hash.
  the_frequencies = Hash.new(0)
  # the_frequencies = {}

  # 3.) iterate of the words array
  words.each do |word|
    # 4.) create a key value pair where the word is the key and the value is the frequency
    the_frequencies[word] += 1
  end
  # 5.) return the hash
  the_frequencies
end

# Separate method to read the text from the 'article.txt' file
def read_file(path)
  File.open(path).read.strip
end

# example:
text = read_file('article.txt')
p frequencies(text)

frequencies_spec.rb

require_relative "../frequencies"

describe "#frequencies" do
  it "returns an empty Hash when passed an empty string" do
    the_frequencies = frequencies("")
    expect(the_frequencies).to eq({})
  end

  it "counts multiple words" do
    the_frequencies = frequencies("the lazy dog jumped over the brown fox")
    expect(the_frequencies["the"]).to eq(2)
    expect(the_frequencies["dog"]).to eq(1)
    expect(the_frequencies["cat"]).to eq(0)
  end
end

interface.rb

require_relative "frequencies"

article = read_file("article.txt")
words = frequencies(article)

# here we sort the words in the hash by their frequency
words.sort_by { |word, frequency| frequency }.reverse.each do |word, frequency|
  puts "#{frequency.to_s.rjust(2)}: #{word}"
end