Ruby - Day 2

Access-files.rb

# With block - closes file automatically
File.open("test.txt") do |file|
  puts file.readlines
end

# Without block
file = File.open("test.txt")
puts file.readlines
file.close

array-to-hash-and-back.rb

# Convert hash to array
my_hash = {:jo => "developer", :barry => "pm", :brett => "ba", :david => "developer"}
my_array = my_hash.to_a

# Convert array to hash
my_nested_array = [[:jo, "developer"], [:barry, "pm"], [:brett, "ba"], [:david, "developer"]]
hash_from_nested_array = Hash[my_nested_array]

hash_from_flat_array = Hash["jo", "developer", "barry", "pm"]

grep-file.rb

puts "Which file should I look at?"
file_name = gets().strip

puts "Enter a phrase to search for?"
phrase = gets().strip
regex = Regexp.new(phrase)

File.open(file_name) do |file|
  
  linenum = 0
  matches = 0
  file.readlines().each do |line|
    linenum+=1
    unless regex.match(line).nil?
      puts "#{phrase} is contained in line #{linenum}: #{line}"
      matches+=1
    end
  end
  puts "Total matches: #{matches}"
end

hash-iteration.rb

my_hash = { "a" => 1, "b" => 2}

my_hash.each {|key,val| puts "#{key} has a value of #{val}"}
my_hash.each_pair {|key,val| puts "#{key} has a value of #{val}"}
my_hash.each_key { |key| puts "#{key} has a value of #{my_hash.fetch(key)}" }
my_hash.each_value {|val| puts "Hash contains value #{val}"}

print-sixteen-numbers.rb

sixteen_numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]

# yuck. really do not like this solution with 'each'

puts "Next 4"
sixteen_numbers.each do |num|
  print num if (1..4).include?(num)
end

puts
puts "Next 4"
sixteen_numbers.each do |num|
  print num if (5..8).include?(num)
end

puts
puts "Next 4"
sixteen_numbers.each do |num|
  print num if (9..12).include?(num)
end

puts
puts "Next 4"
sixteen_numbers.each do |num|
  print num if (13..16).include?(num)
end

puts
puts "each_slice method"
sixteen_numbers.each_slice(4) {|nums| puts "Next 4: #{nums}"}

tree-walker.rb

class Tree
  attr_accessor :children, :node_name

  def initialize(name, treedef)
    @node_name = name
    @children = []
    treedef.each { |key,val| @children << Tree.new(key, val)}
  end

  def visit_all(&block)
    visit &block
    @children.each {|c| c.visit_all &block}
  end

  def visit(&block)
    block.call self
  end
end

#ruby_tree = Tree.new("Ruby", [Tree.new("Reia"), Tree.new("MacRuby")])
family_tree = Tree.new("Family", {'grandpa' => {'dad' => {'child 1'=> {}, 'child 2' => {}}, 'uncle' => {'child 3' => {}, 'child 4' => {}}}})

puts "Visiting a node"
family_tree.visit { |node| puts node.node_name}
puts

puts "Visiting entire tree"
family_tree.visit_all {|node| puts node.node_name}