{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ■マージ"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{:one=>\"A\", :two=>\"B\", :three=>\"C\"}"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a = {one: 'A', two: nil}\n",
    "b = {two: 'B', three: 'C'}\n",
    "\n",
    "a.merge(b)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{:alice=>\"ありす\", :bob=>\"ボブ\"}"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def keywords(**options)\n",
    "  defaults = {alice: 'ありす', bob: 'ぼぶ'}\n",
    "  hash     = defaults.merge(options)\n",
    "  \n",
    "  hash\n",
    "end\n",
    "\n",
    "keywords bob: 'ボブ'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{:one=>\"A\", :two=>\"B\"}\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "{:one=>\"A\", :two=>\"B\"}"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash = {one: 'A'}\n",
    "\n",
    "p(hash.merge! two: 'B')\n",
    "hash"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ■キーと値の入れ替え"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{1=>:one, 2=>:two}\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "{1=>:bar}"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "p({one: 1, two: 2}.invert)\n",
    "{foo: 1, bar: 1}.invert"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ■キーや値が存在しているか"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "nil\n",
      "nil\n",
      "false\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash = {foo: nil}\n",
    "\n",
    "p(hash[:unknown])\n",
    "p(hash[:foo])\n",
    "\n",
    "p(hash.has_key?(:unknown))\n",
    "hash.has_key?(:foo)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "true\n",
      "true\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "p(hash.key?(:foo))\n",
    "p(hash.member?(:foo))\n",
    "hash.include?(:foo)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{:foo=>nil}"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"buzz\""
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash[:bar] = 'buzz'\n",
    "hash&.[](:bar)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"buzz\""
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash&.fetch(:bar)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "nil\n"
     ]
    }
   ],
   "source": [
    "hash2 = nil\n",
    "p(hash2&.fetch(:bar))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "true\n",
      "false\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash = {foo: 'bar'}\n",
    "\n",
    "p(hash.has_value?('bar'))\n",
    "p(hash.has_value?('buzz'))\n",
    "\n",
    "hash.value?('bar') #O(N)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ■キーや値の取得"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[:one, :two, :three]"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "h = {one: 'A', two: 'B', three: 'C'}\n",
    "h.keys"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":two"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "h = {one: 'A', two: 'B', three: 'C'}\n",
    "h.key('B')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[\"A\", \"B\", \"C\"]\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[\"C\", \"B\"]"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "h = {one: 'A', two: 'B', three: 'C'}\n",
    "\n",
    "p(h.values)\n",
    "h.values_at(:three, :two)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\"B\"\n",
      "\"C\"\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[\"B\", \"C\"]"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "three, two = h.values_at(:three, :two)\n",
    "\n",
    "p(two, three)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1865\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "1865"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash = {\n",
    "    alice: {books: {wonder: 1865}},\n",
    "    charlie: {}\n",
    "}\n",
    "\n",
    "p(hash[:alice][:books][:wonder])\n",
    "hash.dig(:alice, :books, :wonder)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "ename": "NoMethodError",
     "evalue": "undefined method `[]' for nil:NilClass",
     "output_type": "error",
     "traceback": [
      "\u001b[31mNoMethodError\u001b[0m: undefined method `[]' for nil:NilClass",
      "\u001b[37m(pry):70:in `<main>'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:355:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:355:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:323:in `handle_line'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:243:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:242:in `catch'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:242:in `block in eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:241:in `catch'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:241:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/backend.rb:65:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/bin/iruby:22:in `load'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/bin/iruby:22:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "hash[:charlie][:books][:chocolate]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "hash.dig(:charlie, :books, :chocolate)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"alice\""
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash = {a: [{word: 'alice'}, {word: 'alpha'}]}\n",
    "hash.dig(:a, 0, :word) \n",
    "# #dig methodがあれば、それを再帰的に掘る"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ■デフォルト値"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"undefined\""
      ]
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "has_default = Hash.new('undefined')\n",
    "has_default['foo']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"evian\""
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "has_default = Hash.new('naive')\n",
    "value = has_default['foo']\n",
    "\n",
    "value.reverse!\n",
    "\n",
    "has_default['foo']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{}"
      ]
     },
     "execution_count": 26,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "hash = Hash.new{|h, k| h[k] = 0}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{\"a\"=>1, \"b\"=>2, \"c\"=>1}"
      ]
     },
     "execution_count": 27,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "['a', 'b', 'b', 'c'].each do |v|\n",
    "  hash[v] += 1\n",
    "end\n",
    "hash"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "nil\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "\"bar\""
      ]
     },
     "execution_count": 29,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "has_default = {}\n",
    "p(has_default['foo'])\n",
    "\n",
    "has_default.default = 'bar'\n",
    "has_default['foo']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "2017-06-28 20:17:22 +0900"
      ]
     },
     "execution_count": 31,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "has_default.default_proc = ->(has, key) {Time.now}\n",
    "has_default['foo']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\"default\"\n",
      "\"foo\"\n"
     ]
    },
    {
     "ename": "KeyError",
     "evalue": "key not found: \"foo\"",
     "output_type": "error",
     "traceback": [
      "\u001b[31mKeyError\u001b[0m: key not found: \"foo\"",
      "\u001b[37m(pry):107:in `fetch'\u001b[0m",
      "\u001b[37m(pry):107:in `<main>'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:355:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:355:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:323:in `handle_line'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:243:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:242:in `catch'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:242:in `block in eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:241:in `catch'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:241:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/backend.rb:65:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/bin/iruby:22:in `load'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.4.0-preview2/bin/iruby:22:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "hash = {}\n",
    "p(hash.fetch('foo', 'default'))\n",
    "p(hash.fetch('foo'){|k| k})\n",
    "hash.fetch('foo')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### ■ハッシュの変換"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[:one, 1], [:two, 2]]\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[:one, 1]"
      ]
     },
     "execution_count": 34,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a = {one: 1, two: 2}.to_a\n",
    "p a\n",
    "\n",
    "a.assoc(:one)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[:one, 1, \"1\"]"
      ]
     },
     "execution_count": 35,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a1 = [[:one, 1, '1']]\n",
    "a1.assoc(:one)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{\"key1\"=>\"one\", \"key2\"=>\"two\"}\n",
      "{\"key1\"=>\"one\", \"key2\"=>\"two\"}\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "{\"key1\"=>\"one\", \"key2\"=>\"two\"}"
      ]
     },
     "execution_count": 36,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ary = ['key1', 'one', 'key2', 'two']\n",
    "p(Hash[*ary])\n",
    "\n",
    "ary = [['key1', 'one'], ['key2', 'two']]\n",
    "p(Hash[ary])\n",
    "\n",
    "ary.to_h"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "次回は 5-5-4 Enumerator から"
   ]
  }
 ],
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