Seven Languages in Seven Weeks: A Pragmatic Guide to Learning Programming Languages (Ruby 2nd)

b.rb

#!/usr/bin/env ruby
arr = (1..16).to_a
tmp = []
arr.each do |val|
  tmp.push(val)
  if tmp.length == 4
    puts tmp.join(",") 
    tmp = []
  end
end

b.rb-result.txt

bash$ ./b.rb
1,2,3,4
5,6,7,8
9,10,11,12
13,14,15,16
bash$ 

c.rb

#!/usr/bin/env ruby
arr = (1..16).to_a
arr.each_slice(4) do |val|
  puts val.join(",") 
end

c.rb-result.txt

bash$ ./c.rb
1,2,3,4
5,6,7,8
9,10,11,12
13,14,15,16
bash$ 

d.rb

#!/usr/bin/env ruby

tree_data = {
  'grandpa' => {
    'dad' => {
      'child 1'=>[],
      'child 2'=>[]
    },
    'uncle' => {
      'child 3'=>[],
      'child 4'=>[]
    }
  }
}

class Tree
  attr_reader :children, :node_name
# あえてデバッグ用出力を残してみた
  def initialize(tree)
puts "---"
p tree
    tree = tree.to_a[0] if tree.is_a?(Hash)
p tree[0]
    @node_name = tree[0]
    @children = []
    tree[1].each do |subtree|
p subtree
      @children.push(Tree.new(subtree))
    end
puts "---"
  end

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

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

all_tree = Tree.new(tree_data)

all_tree.visit_all do |tree|
  puts "#{tree.node_name} has children(#{tree.children.size})"
end

d.rb-result.txt

bash$ ./d.rb
---
{"grandpa"=>{"dad"=>{"child 1"=>[], "child 2"=>[]}, "uncle"=>{"child 3"=>[], "child 4"=>[]}}}
"grandpa"
["dad", {"child 1"=>[], "child 2"=>[]}]
---
["dad", {"child 1"=>[], "child 2"=>[]}]
"dad"
["child 1", []]
---
["child 1", []]
"child 1"
---
["child 2", []]
---
["child 2", []]
"child 2"
---
---
["uncle", {"child 3"=>[], "child 4"=>[]}]
---
["uncle", {"child 3"=>[], "child 4"=>[]}]
"uncle"
["child 3", []]
---
["child 3", []]
"child 3"
---
["child 4", []]
---
["child 4", []]
"child 4"
---
---
---
grandpa has children(2)
dad has children(2)
child 1 has children(0)
child 2 has children(0)
uncle has children(2)
child 3 has children(0)
child 4 has children(0)
#<Tree:0x007fa2bb906ce8 @node_name="grandpa", @children=[#<Tree:0x007fa2bb9067e8 @node_name="dad", @children=[#<Tree:0x007fa2bb906590 @node_name="child 1", @children=[]>, #<Tree:0x007fa2bb9063b0 @node_name="child 2", @children=[]>]>, #<Tree:0x007fa2bb906108 @node_name="uncle", @children=[#<Tree:0x007fa2bb905eb0 @node_name="child 3", @children=[]>, #<Tree:0x007fa2bb905cd0 @node_name="child 4", @children=[]>]>]>
bash$ 

e.rb

#!/usr/bin/env ruby

re = Regexp.compile(ARGV[0])
File.open(ARGV[1]) do |infile|
  infile.each_with_index do |line, i|
    puts "#{i}: #{line}" if re =~ line
  end
end

e.rb-result.txt

bash$ ./e.rb f ./e.rb
3: File.open(ARGV[1]) do |infile|
4:   infile.each_with_index do |line, i|
5:     puts "#{i}: #{line}" if re =~ line
bash$