6-Loops.ipynb

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   "source": [
    "# Table of Contents\n",
    " <p><div class=\"lev1 toc-item\"><a href=\"#Loops-(while/for/内包表記)\" data-toc-modified-id=\"Loops-(while/for/内包表記)-1\"><span class=\"toc-item-num\">1&nbsp;&nbsp;</span>Loops (while/for/内包表記)</a></div><div class=\"lev2 toc-item\"><a href=\"#while\" data-toc-modified-id=\"while-11\"><span class=\"toc-item-num\">1.1&nbsp;&nbsp;</span>while</a></div><div class=\"lev2 toc-item\"><a href=\"#for\" data-toc-modified-id=\"for-12\"><span class=\"toc-item-num\">1.2&nbsp;&nbsp;</span>for</a></div><div class=\"lev2 toc-item\"><a href=\"#少し書き方が特殊なループ\" data-toc-modified-id=\"少し書き方が特殊なループ-13\"><span class=\"toc-item-num\">1.3&nbsp;&nbsp;</span>少し書き方が特殊なループ</a></div><div class=\"lev1 toc-item\"><a href=\"#内包表記\" data-toc-modified-id=\"内包表記-2\"><span class=\"toc-item-num\">2&nbsp;&nbsp;</span>内包表記</a></div>"
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   "source": [
    "# Loops (while/for/内包表記)\n",
    "\n",
    "JuliaのLoopは、どうもこの２つみたいなので、これについて勉強します。"
   ]
  },
  {
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   "metadata": {},
   "source": [
    "## while\n",
    "\n",
    "whileを用いたループ処理は、以下のような形で書く。\n",
    "\n",
    "```\n",
    "while *condition*\n",
    "    *loop*\n",
    "end\n",
    "```"
   ]
  },
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      "1\n",
      "2\n",
      "3\n",
      "4\n",
      "5\n",
      "6\n",
      "7\n",
      "8\n",
      "9\n",
      "10\n"
     ]
    }
   ],
   "source": [
    "i = 0\n",
    "# pythonだと、コロンをつけるが、juliaはendでwhileの終わりを判定しているので、つけない。。。\n",
    "# 違和感。。。\n",
    "while i < 10\n",
    "    i += 1\n",
    "    println(i)\n",
    "end"
   ]
  },
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "apple\n",
      "banana\n",
      "orange\n"
     ]
    }
   ],
   "source": [
    "fruits = [\"apple\", \"banana\", \"orange\"]\n",
    "\n",
    "i = 1\n",
    "while i <= length(fruits)\n",
    "    println(fruits[i])\n",
    "    i += 1\n",
    "end"
   ]
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   "source": [
    "## for\n",
    "\n",
    "以下のような形で書く。\n",
    "\n",
    "```\n",
    "for *var* in *loop iterable*\n",
    "    *loop body*\n",
    "end\n",
    "```\n"
   ]
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     "text": [
      "1\n",
      "2\n",
      "3\n",
      "4\n",
      "5\n"
     ]
    }
   ],
   "source": [
    "# for loopはPythonに似たような感じの使い方ができる。\n",
    "# こちらも、コロンではなくて、endで、ループのbodyの箇所を判定する\n",
    "for i = 1:5\n",
    "    println(i)\n",
    "end"
   ]
  },
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   "cell_type": "code",
   "execution_count": 4,
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "apple\n",
      "banana\n",
      "orange\n"
     ]
    }
   ],
   "source": [
    "# iterableであればいいので、配列のループもできる\n",
    "fruits = [\"apple\", \"banana\", \"orange\"]\n",
    "\n",
    "for i in fruits\n",
    "    println(i)\n",
    "end"
   ]
  },
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    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "apple\n",
      "banana\n",
      "orange\n"
     ]
    }
   ],
   "source": [
    "# タプルもできる\n",
    "fruits = (\"apple\", \"banana\", \"orange\")\n",
    "\n",
    "for i in fruits\n",
    "    println(i)\n",
    "end"
   ]
  },
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   "cell_type": "code",
   "execution_count": 6,
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "orange は 3 個あります\n",
      "banana は 2 個あります\n",
      "apple は 1 個あります\n"
     ]
    }
   ],
   "source": [
    "# 辞書も試してみる。\n",
    "fruits = Dict(\"apple\" => 1, \"banana\" => 2, \"orange\" => 3)\n",
    "\n",
    "# ちなみに、カッコをつけないとエラーになるので注意\n",
    "for (k, v) in fruits\n",
    "    println(\"$k は $v 個あります\")\n",
    "end"
   ]
  },
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   "cell_type": "code",
   "execution_count": 7,
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "a\n",
      "p\n",
      "p\n",
      "l\n",
      "e\n"
     ]
    }
   ],
   "source": [
    "# 文字列のループも試してみる\n",
    "apple = \"apple\"\n",
    "\n",
    "# pythonと同じくこれもiterableなので、できる。\n",
    "for i in apple\n",
    "    println(i)\n",
    "end"
   ]
  },
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   "metadata": {},
   "source": [
    "## 少し書き方が特殊なループ\n",
    "\n",
    "Pythonとは少し違う書き方をするループの書き方を見ておきます。"
   ]
  },
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   "execution_count": 8,
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 2)\n",
      "(1, 3)\n",
      "(2, 2)\n",
      "(2, 3)\n"
     ]
    }
   ],
   "source": [
    "# 2つ以上の配列をループする\n",
    "# この書き方をすると、Pythonだと2重ループみたいに書かないといけないところが、一行でかけるようになる。\n",
    "for i = 1:2, j = 2:3\n",
    "    println((i, j))\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2018-02-07T11:22:40.731000Z",
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   },
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    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 2)\n",
      "(1, 3)\n",
      "(1, 4)\n",
      "(1, 5)\n",
      "(2, 2)\n",
      "(2, 3)\n",
      "(2, 4)\n",
      "(2, 5)\n"
     ]
    }
   ],
   "source": [
    "# 1つのループではないので、以下のように要素の数が違っていても良い。\n",
    "for i = 1:2, j = 2:5\n",
    "    println((i, j))\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
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     "end_time": "2018-02-07T11:22:40.917000Z",
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    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 3)\n",
      "(2, 4)\n"
     ]
    }
   ],
   "source": [
    "# 同時にループを回したい場合は、zip関数を使う\n",
    "for (i, j) in zip(1:2, 3:4)\n",
    "    println((i, j))\n",
    "end"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 内包表記\n",
    "\n",
    "pythonでは非常によく使う内包表記だが、これをJuliaでもできるので、試す"
   ]
  },
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   "cell_type": "code",
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "3-element Array{String,1}:\n",
       " \"apple\" \n",
       " \"banana\"\n",
       " \"orange\""
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# なんの意味もない例だが、以下のようにできる\n",
    "fruits = [i for i in [\"apple\", \"banana\", \"orange\"]]"
   ]
  },
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    "scrolled": true
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    {
     "data": {
      "text/plain": [
       "100×100 Array{Int64,2}:\n",
       " 102  103  104  105  106  107  108  109  …  195  196  197  198  199  200  201\n",
       " 103  104  105  106  107  108  109  110     196  197  198  199  200  201  202\n",
       " 104  105  106  107  108  109  110  111     197  198  199  200  201  202  203\n",
       " 105  106  107  108  109  110  111  112     198  199  200  201  202  203  204\n",
       " 106  107  108  109  110  111  112  113     199  200  201  202  203  204  205\n",
       " 107  108  109  110  111  112  113  114  …  200  201  202  203  204  205  206\n",
       " 108  109  110  111  112  113  114  115     201  202  203  204  205  206  207\n",
       " 109  110  111  112  113  114  115  116     202  203  204  205  206  207  208\n",
       " 110  111  112  113  114  115  116  117     203  204  205  206  207  208  209\n",
       " 111  112  113  114  115  116  117  118     204  205  206  207  208  209  210\n",
       " 112  113  114  115  116  117  118  119  …  205  206  207  208  209  210  211\n",
       " 113  114  115  116  117  118  119  120     206  207  208  209  210  211  212\n",
       " 114  115  116  117  118  119  120  121     207  208  209  210  211  212  213\n",
       "   ⋮                        ⋮            ⋱              ⋮                    \n",
       " 190  191  192  193  194  195  196  197     283  284  285  286  287  288  289\n",
       " 191  192  193  194  195  196  197  198     284  285  286  287  288  289  290\n",
       " 192  193  194  195  196  197  198  199  …  285  286  287  288  289  290  291\n",
       " 193  194  195  196  197  198  199  200     286  287  288  289  290  291  292\n",
       " 194  195  196  197  198  199  200  201     287  288  289  290  291  292  293\n",
       " 195  196  197  198  199  200  201  202     288  289  290  291  292  293  294\n",
       " 196  197  198  199  200  201  202  203     289  290  291  292  293  294  295\n",
       " 197  198  199  200  201  202  203  204  …  290  291  292  293  294  295  296\n",
       " 198  199  200  201  202  203  204  205     291  292  293  294  295  296  297\n",
       " 199  200  201  202  203  204  205  206     292  293  294  295  296  297  298\n",
       " 200  201  202  203  204  205  206  207     293  294  295  296  297  298  299\n",
       " 201  202  203  204  205  206  207  208     294  295  296  297  298  299  300"
      ]
     },
     "execution_count": 12,
     "metadata": {},
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    }
   ],
   "source": [
    "# 2重の内包表記も可能\n",
    "fruits_num = [i + j for i in 1:100, j in 101:200]"
   ]
  }
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