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  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# Efficient String Concatenation in Python\n",
      "\n",
      "## \uc6d0\ubcf8 \uc790\ub8cc\n",
      "\n",
      "- [Efficient String Concatenation in Python](http://www.skymind.com/~ocrow/python_string/)\n"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Introduction\n",
      "\n",
      "- long strings in the Python programming language can sometimes result in very slow running code\n",
      "- In Python the **string** object is **immutable**: **each time** a string is **assigned** to a variable a new object is created in memory to represent the **new value**\n",
      "- \ub9e4\ubc88 \ubb38\uc790\uc5f4 \ub9c8\uc9c0\ub9c9\uc5d0 \uc0c8\ub85c\uc6b4 \ubb38\uc790\uc5f4\uc744 \ubd99\uc774\uac8c \ub418\uba74 \ub9e4\ubc88 \ubb38\uc790\uc5f4\uc744 \uc0c8\ub85c \uc0dd\uc131\ud55c\ub2e4.\n",
      "- \ub611\uac19\uc740 \uac78 \ub610 \ubcf5\uc0ac\ud558\uace0 \uadf8 \ub4a4\uc5d0 \ucd94\uac00\ud558\uac8c \ub41c\ub2e4. \uadf8\ub798\uc11c \ub9ce\uc740 string\uc744 \ub2e4\ub8f0 \ub54c \ub290\ub824\uc9c0\uac8c \ub41c\ub2e4."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Six Method\n",
      "\n",
      "### Method 1: Naive appending\n",
      "\n",
      "- backticks(``): int -> str, str()\uacfc \uac19\uc740 \uc5ed\ud560"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "!python --version"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Python 2.7.6\r\n"
       ]
      }
     ],
     "prompt_number": 102
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "loop_count = 100"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 50
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def method1():\n",
      "    out_str = ''\n",
      "    for num in xrange(loop_count):\n",
      "        out_str += `num`\n",
      "    return out_str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 281
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# backticks: int -> str\n",
      "`10`"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 52,
       "text": [
        "'10'"
       ]
      }
     ],
     "prompt_number": 52
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "str(10)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 53,
       "text": [
        "'10'"
       ]
      }
     ],
     "prompt_number": 53
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "method1()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 54,
       "text": [
        "'0123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899'"
       ]
      }
     ],
     "prompt_number": 54
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit?"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 30
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method1()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1000000 loops, best of 3: 1.25 \u00b5s per loop\n"
       ]
      }
     ],
     "prompt_number": 37
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit -n 1000 -r 10 method1()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1000 loops, best of 10: 9.94 \u00b5s per loop\n"
       ]
      }
     ],
     "prompt_number": 55
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit -n 1000 -r 10 -p 3 -o method1()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1000 loops, best of 10: 10.1 \u00b5s per loop\n"
       ]
      },
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 56,
       "text": [
        "<TimeitResult : 1000 loops, best of 10: 10.1 \u00b5s per loop>"
       ]
      }
     ],
     "prompt_number": 56
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit -n 1000 method1()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1000 loops, best of 3: 10.1 \u00b5s per loop\n"
       ]
      }
     ],
     "prompt_number": 57
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%%timeit?"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 31
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Method 2: MutableString class\n",
      "\n",
      "- [string - Why is MutableString deprecated in Python? - Stack Overflow](http://stackoverflow.com/questions/4651344/why-is-mutablestring-deprecated-in-python)\n",
      "- Mutablestring \ud074\ub798\uc2a4\uac00 \uc5c6\ub2e4. \uc0ac\ub77c\uc9d0"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def method2():\n",
      "    from UserString import MutableString\n",
      "    out_str = MutableString()\n",
      "    for num in xrange(loop_count):\n",
      "        out_str += `num`\n",
      "    return out_str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 282
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Method 3: Character arrays\n",
      "\n",
      "- c\uc758 array\ub85c \ub9cc\ub4e4\uace0\n",
      "- fromstring\uc73c\ub85c string\uc73c\ub85c \uac00\uc838\uc640\uc11c \ubc30\uc5f4\uc758 \ub05d\uc5d0 \ucd94\uac00\ud55c\ub2e4.\n",
      "- \ub9c8\uc9c0\ub9c9\uc73c\ub85c tostring() \ud574\uc11c string\uc73c\ub85c \ub9cc\ub4e0\ub2e4.\n",
      "\n",
      "\n",
      "- Arryas are mutable in python. \uadf8\ub798\uc11c \uc6d0\ub798 \uc788\ub358 \ubb38\uc790\uc5f4\uc740 \ubcf5\uc0ac\ud558\uc9c0 \uc54a\ub294\ub2e4."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def method3():\n",
      "    from array import array\n",
      "    char_array = array('c')\n",
      "    for num in xrange(loop_count):\n",
      "        char_array.fromstring(`num`)\n",
      "    return char_array.tostring()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 283
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "method3()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 284,
       "text": [
        "'012345678910111213141516171819'"
       ]
      }
     ],
     "prompt_number": 284
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from array import array"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 60
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "char_array = array('c')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 61
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "char_array"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 62,
       "text": [
        "array('c')"
       ]
      }
     ],
     "prompt_number": 62
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "char_array.fromstring(`5`)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 63
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "char_array"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 64,
       "text": [
        "array('c', '5')"
       ]
      }
     ],
     "prompt_number": 64
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "char_array.fromstring(`6`)\n",
      "char_array"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 65,
       "text": [
        "array('c', '56')"
       ]
      }
     ],
     "prompt_number": 65
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "char_array.tostring()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 66,
       "text": [
        "'56'"
       ]
      }
     ],
     "prompt_number": 66
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Method 4: Build a list of strings, then join it\n",
      "\n",
      "- \uc774 \ubc29\ubc95\uc744 \ucd94\ucc9c\ud55c\ub2e4. \ub9e4\uc6b0 \ud30c\uc774\uc36c\uc2a4\ub7fd\ub2e4."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def method4():\n",
      "    str_list = []\n",
      "    for num in xrange(loop_count):\n",
      "        str_list.append(`num`)\n",
      "    out_str = ''.join(str_list)\n",
      "    return out_str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 285
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "#### lookup \ubd80\ud558 \uc904\uc774\uae30(\uae40\ud0dc\ud638\ub2d8 \uc758\uacac)\n",
      "\n",
      "- l.append\ub97c ll\ub85c \ubcc0\uacbd\n",
      "- .\uc5f0\uc0b0\uc790\uac00 \uc788\uc73c\uba74 \ucc38\uc870\ud558\uae30 \uc704\ud574 \ub290\ub824\uc9c0\uae30 \ub54c\ubb38\uc5d0 \uadf8 \ucc38\uc870\ud558\ub294 \uc18d\ub3c4\ub3c4 \uc904\uc774\uae30 \uc704\ud568\n",
      "- for\ubb38 \uc548\uc5d0\uc11c \uadf9\ud55c\uc758 \uc18d\ub3c4\ub97c \uc5bb\uae30 \uc704\ud574\uc11c\ub294 .\uc73c\ub85c \ucc38\uc870\ud558\ub294 \uac83\ub3c4 \uc0ac\uc6a9\ud558\uc9c0 \ub9d0\uc790"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "l = []"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 374
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "ll = l.append"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 375
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "ll(1)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 376
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "ll"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 377,
       "text": [
        "<function append>"
       ]
      }
     ],
     "prompt_number": 377
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "ll(10)\n",
      "l"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 378,
       "text": [
        "[1, 10]"
       ]
      }
     ],
     "prompt_number": 378
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def method4_2():\n",
      "    str_list = []\n",
      "    str_list2 = str_list.append\n",
      "    for num in xrange(loop_count):\n",
      "        str_list2(`num`)\n",
      "    out_str = ''.join(str_list)\n",
      "    return out_str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 310
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Method 5: Write to a pseudo file\n",
      "\n",
      "- \ud30c\uc77c\ucc98\ub7fc \uc800\uc7a5\ub41c\ub2e4. \ud558\uc9c0\ub9cc \uc800\uc7a5\ub418\ub294 \uac83\uc740 string.\n",
      "- \uba85\ud655\ud558\uac8c \ud30c\uc77c\uc5d0 \ucd94\uac00\ud558\ub294 \uac83\uc740 \ub9e4\uc6b0 \uc27d\ub2e4."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def method5():\n",
      "    from cStringIO import StringIO\n",
      "    file_str = StringIO()\n",
      "    for num in xrange(loop_count):\n",
      "        file_str.write(`num`)\n",
      "    out_str = file_str.getvalue()\n",
      "    return out_str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 286
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Method 6: List comprehensions\n",
      "\n",
      "- Method4\uc640 \uac19\uc740\ub370 list.append()\ub97c \uac01 loop\uc5d0\uc11c \ubd80\ub974\uc9c0 \uc54a\uae30 \ub54c\ubb38\uc5d0 \uc18d\ub3c4 \ud5a5\uc0c1\uc774 \uc788\ub2e4.\n",
      "- \ub9e4\uc6b0 \uc9e7\uc740 \ucf54\ub4dc\ub2e4.\n",
      "- join, list comprehension\uc744 \ub3d9\uc2dc\uc5d0 \uc0ac\uc6a9\ud588\ub2e4"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def method6():\n",
      "    out_str = ''.join([`num` for num in xrange(loop_count)])\n",
      "    return out_str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 287
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# generator\ub85c \uc0dd\uc131\n",
      "def method7():\n",
      "    out_str = ''.join((`num` for num in xrange(loop_count)))\n",
      "    return out_str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 288
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Results\n",
      "\n",
      "### Results: Twenty thousand integers(20,000)"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "loop_count = 20000"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 320
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method1()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100 loops, best of 3: 2.58 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 321
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method2()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method3()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100 loops, best of 3: 6.45 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 322
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method4()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100 loops, best of 3: 2.84 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 323
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# \ud655\uc2e4\ud788 \ube68\ub77c\uc84c\ub2e4!\n",
      "%timeit method4_2()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100 loops, best of 3: 2.07 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 324
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method5()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100 loops, best of 3: 7.66 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 325
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method6()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1000 loops, best of 3: 1.76 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 326
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method7()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100 loops, best of 3: 2.1 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 327
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### \uc18d\ub3c4\n",
      "\n",
      "- [\ub2f9\ub2f9\ud55c \uc790\uae30\ud45c\ud604 : \ucef4\ud4e8\ud130 ms, us, ns, ps, fs, as](http://sea1sun.egloos.com/viewer/8879042)\n",
      "\n",
      "#### \ucef4\ud4e8\ud130 \ucc98\ub9ac \uc18d\ub3c4 \ub2e8\uc704\n",
      "\n",
      "- \ubc00\ub9ac\ucd08(ms) : 1/1,000\ucd08\n",
      "- \ub9c8\uc774\ud06c\ub85c\ucd08(\u03bcs) : 1/1,000,000\ucd08\n",
      "- \ub098\ub178\ucd08(ns) : 1/1,000,000,000\ucd08\n",
      "- \ud53c\ucf54\ucd08(ps) : 1/1,000,000,000,000\ucd08\n",
      "- \ud3a8\ud1a0\ucd08(fs) : 1/1,000,000,000,000,000\ucd08\n",
      "- \uc544\ud1a0\ucd08(as) : 1/1,000,000,000,000,000,000\ucd08\n",
      "- ms : \ubc00\ub9ac\ucd08 0.001 = 10^(-3)\ucd08\n",
      "- \u33b2 : \ub9c8\uc774\ud06c\ub85c\ucd08 0.000001\ucd08 = 10^(-6)\ucd08\n",
      "- \u33b1: \ub098\ub178\ucd08 0.000000001\ucd08 = 10^(-9)\ucd08\n",
      "- \u33b0 : \ud53c\ucf54\ucd08 0.000000000001\ucd08 = 10^(-12)\ucd08\n",
      "- fs : \ud3a8\ud1a0\ucd08 0.000000000000001\ucd08 = 10^(-15)\ucd08\n",
      "- as : \uc544\ud1a0\ucd08 0.000000000000000001\ucd08 = 10^(-18)\ucd08\n",
      "\n",
      "\n",
      "- 1024byte = 1KB (kilo byte)\n",
      "- 1024KB = 1MB (mega byte)\n",
      "- 1024MB = 1GB (giga byte) = 1048576 KB\n",
      "- 1024GB = 1TB (tela byte)\n",
      "- 1024TB = 1PB (peta byte)"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      ">timeit: 100, 1000 loops \uc774\ub4e0 \uc5b4\uc9dc\ud53c best 3\uc758 \uacb0\uacfc\ub9cc \ubcf4\uba74 \ub41c\ub2e4."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### \uc6d0\ub798 \ube14\ub85c\uadf8\uc5d0 \uc788\ub294 Image(\ub0b4 \uc2e4\ud5d8 \uacb0\uacfc\uc640 \ub2e4\ub984)\n",
      "\n",
      "![Concatenations per second(thousands)](http://www.skymind.com/~ocrow/python_string/test_20k.gif)"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### \uacb0\uacfc\uac00 \uc774\uc0c1\ud55c\ub370?\n",
      "\n",
      "1. method6: list comprehension\n",
      "2. method4_2: list append(.\uc5f0\uc0b0\uc790 \uc811\uadfc \uc5c6\uc570)\n",
      "3. method1: string concatenating\n",
      "4. method4: list append\n",
      "\n",
      "\n",
      "- \uc6d0\ub798 \ube14\ub85c\uadf8\uc5d0\uc11c \ubcf4\uc5ec\uc900 \uac83\uacfc \ub2e4\ub978 \uacb0\uacfc\uac00 \ub098\ud0c0\ub09c\ub2e4.\n",
      "- method1\uc774 method4\ubcf4\ub2e4 \ube60\ub978\uac8c \uc774\ud574\uac00 \uc548\ub41c\ub2e4. string\uc774 \ubcc0\uacbd\ub418\uc9c0 \uc54a\ub294 \uac1d\uccb4\uc774\uae30 \ub54c\ubb38\uc5d0 \ub9e4\ubc88 \uc0dd\uc131\ub418\uc11c \ub290\ub9b4\uac83 \uac19\uc740\ub370 \uacb0\uacfc\ub294 \ub354 \ube60\ub974\ub124?(**\uac00\uc7a5 \uc774\ud574 \uc548\ub418\ub294 \uacb0\uacfc**)\n",
      "- method4_2\uc5d0\uc11c **.\uc5f0\uc0b0\uc790\ub85c \ucc38\uace0\ud558\ub294 \uac83\ub3c4 \uc904\uc600\ub354\ub2c8** \uc18d\ub3c4\uac00 \uc880 \ub354 **\ube68\ub77c\uc84c\ub2e4**.\n",
      "- method5 \uac19\uc740 \uacbd\uc6b0\uc5d0\ub294 memory\uc5d0 \uc4f8\uac83 \uac19\uc740\ub370 \uc2e4\uc81c temp \ud30c\uc77c\ub85c \uc4f0\ub098? \uc65c \uc774\ub9ac \uc18d\ub3c4\uac00 \ub290\ub9ac\uc9c0?\n",
      "- \ucc38\uace0\ub85c \ub0b4 \ucef4\ud4e8\ud130\ub294 \ub9e5\ubd81 \ud504\ub85c \ub808\ud2f0\ub098\uc784\n",
      "\n",
      "### Profiling\n",
      "\n",
      "- \ud504\ub85c\ud30c\uc77c\ub9c1\uc744 \ud558\uba74 \uc5b4\ub5a4 \ud568\uc218\uc5d0\uc11c \uc2dc\uac04\uc774 \uc624\ub798 \uc18c\ubaa8\ub418\ub294\uc9c0 \uc54c \uc218 \uc788\uc73c\ub2c8\uae4c \uc88b\uc744\uac83 \uac19\uc740\ub370?\n",
      "- \ud504\ub85c\ud30c\uc77c\ub9c1\uc5d0 \ub300\ud574\uc11c \ud55c \ubc88 \uc870\uc0ac\ub97c \ud574\ubd10\uc57c\uaca0\ub2e4"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "loop_count = 500000"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 96
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method1()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10 loops, best of 3: 84.7 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 97
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method2()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method3()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1 loops, best of 3: 178 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 98
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method4()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10 loops, best of 3: 90 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 99
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method5()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1 loops, best of 3: 197 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 100
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit method6()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10 loops, best of 3: 62.8 ms per loop\n"
       ]
      }
     ],
     "prompt_number": 101
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### timeit\uc774 \uc798\ubabb\ub410\ub098? \ub0b4\uac00 \uc9c1\uc811 \uc9dc\ubcf4\uc790"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import time\n",
      "def check_time(func):\n",
      "    def inner(*args, **kwargs):\n",
      "        start = time.time()\n",
      "        for i in range(10):\n",
      "            ret = func(*args, **kwargs)\n",
      "        end = time.time()\n",
      "        print '%.8f' % (end - start)\n",
      "        return ret\n",
      "    return inner"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 123
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "@check_time\n",
      "def method1():\n",
      "    out_str = ''\n",
      "    for num in xrange(loop_count):\n",
      "        out_str += `num`\n",
      "#     return out_str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 135
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "@check_time\n",
      "def method3():\n",
      "    from array import array\n",
      "    char_array = array('c')\n",
      "    for num in xrange(loop_count):\n",
      "        char_array.fromstring(`num`)\n",
      "    char_array.tostring()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 136
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "@check_time\n",
      "def method4():\n",
      "    str_list = []\n",
      "    for num in xrange(loop_count):\n",
      "        str_list.append(`num`)\n",
      "    ''.join(str_list)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 137
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "@check_time\n",
      "def method5():\n",
      "    from cStringIO import StringIO\n",
      "    file_str = StringIO()\n",
      "    for num in xrange(loop_count):\n",
      "        file_str.write(`num`)\n",
      "    file_str.getvalue()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 138
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "@check_time\n",
      "def method6():\n",
      "    ''.join([`num` for num in xrange(loop_count)])"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 139
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "method1()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "0.87336206\n"
       ]
      }
     ],
     "prompt_number": 140
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "method3()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1.85140491\n"
       ]
      }
     ],
     "prompt_number": 141
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "method4()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "0.94222403\n"
       ]
      }
     ],
     "prompt_number": 142
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "method5()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "2.01019597\n"
       ]
      }
     ],
     "prompt_number": 143
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "method6()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "0.66609311\n"
       ]
      }
     ],
     "prompt_number": 144
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## \ucd5c\uc885 \uacb0\ub860\n",
      "\n",
      "- %timeit\uacfc \ub611\uac19\uc740 \uacb0\uacfc\uac00 \ub098\uc624\ub124\n",
      "- list comprehension\uc744 \uc0ac\uc6a9\ud55c method6\uc774 \ud56d\uc0c1 win"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Original source(\ube14\ub85c\uadf8 \uc8fc\uc778\uc7a5)"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%%writefile tmp/original_str_performance.py\n",
      "\n",
      "\n",
      "from cStringIO import StringIO\n",
      "import time, commands, os\n",
      "from sys import argv\n",
      "\n",
      "def method1():\n",
      "\tout_str = ''\n",
      "\tfor num in xrange(loop_count):\n",
      "\t\tout_str += `num`\n",
      "\tps_stats()\n",
      "\treturn out_str\n",
      "\n",
      "def method2():\n",
      "\tfrom UserString import MutableString\n",
      "\tout_str = MutableString()\n",
      "\tfor num in xrange(loop_count):\n",
      "\t\tout_str += `num`\n",
      "\tps_stats()\n",
      "\treturn out_str\n",
      "\n",
      "def method3():\n",
      "\tfrom array import array\n",
      "\tchar_array = array('c')\n",
      "\tfor num in xrange(loop_count):\n",
      "\t\tchar_array.fromstring(`num`)\n",
      "\tps_stats()\n",
      "\treturn char_array.tostring()\n",
      "\n",
      "def method4():\n",
      "\tstr_list = []\n",
      "\tfor num in xrange(loop_count):\n",
      "\t\tstr_list.append(`num`)\n",
      "\tout_str = ''.join(str_list)\n",
      "\tps_stats()\n",
      "\treturn out_str\n",
      "\n",
      "def method4_2():\n",
      "\tstr_list = []\n",
      "\tstr_list2 = str_list.append\n",
      "\tfor num in xrange(loop_count):\n",
      "\t\tstr_list2(`num`)\n",
      "\tout_str = ''.join(str_list)\n",
      "\tps_stats()\n",
      "\treturn out_str\n",
      "\n",
      "def method5():\n",
      "\tfile_str = StringIO()\n",
      "\tfor num in xrange(loop_count):\n",
      "\t\tfile_str.write(`num`)\n",
      "\tout_str = file_str.getvalue()\n",
      "\tps_stats()\n",
      "\treturn out_str\n",
      "\n",
      "def method6():\n",
      "\tout_str = ''.join([`num` for num in xrange(loop_count)])\n",
      "\tps_stats()\n",
      "\treturn out_str\n",
      "\n",
      "\n",
      "def ps_stats():\n",
      "\tglobal process_size\n",
      "\tps = commands.getoutput('ps -l ' + `pid`)\n",
      "\tprocess_size = ps.split()[23]\n",
      "    \n",
      "\n",
      "def call_method(num):\n",
      "\tglobal process_size\n",
      "\tstart = time.time()\n",
      "\tz = eval('method' + str(num))()\n",
      "\tend = time.time()\n",
      "\tprint \"method\", num\n",
      "\tprint \"time\", float(end-start) * 100\n",
      "\tprint \"output size \", len(z) / 1024, \"kb\"\n",
      "\tprint \"process size\", process_size, \"kb\"\n",
      "\tprint\n",
      "\t\n",
      "loop_count = 100000\n",
      "pid = os.getpid()\n",
      "\n",
      "if len(argv) == 2:\n",
      "\tcall_method(argv[1])\n",
      "else:\n",
      "\tprint \"Usage: python stest.py <n>\\n\" \\\n",
      "\t\t\"  where n is the method number to test\"\n",
      "\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Overwriting tmp/original_str_performance.py\n"
       ]
      }
     ],
     "prompt_number": 379
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "!python tmp/original_str_performance.py 1"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "method 1\r\n",
        "time 2.25088596344\r\n",
        "output size  477 kb\r\n",
        "process size 4616 kb\r\n",
        "\r\n"
       ]
      }
     ],
     "prompt_number": 388
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%run tmp/original_str_performance.py 1"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "method 1\n",
        "time 2.80869007111\n",
        "output size  477 kb\n",
        "process size 59764 kb\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 389
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%run tmp/original_str_performance.py 2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "method 2\n",
        "time 185.649013519\n",
        "output size  477 kb\n",
        "process size 59452 kb\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 390
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%run tmp/original_str_performance.py 3"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "method 3\n",
        "time 4.83219623566\n",
        "output size  477 kb\n",
        "process size 58760 kb\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 391
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "!python tmp/original_str_performance.py 4"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "method 4\r\n",
        "time 2.69351005554\r\n",
        "output size  477 kb\r\n",
        "process size 10336 kb\r\n",
        "\r\n"
       ]
      }
     ],
     "prompt_number": 392
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%run tmp/original_str_performance.py 4_2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "method 4_2\n",
        "time 2.11400985718\n",
        "output size  477 kb\n",
        "process size 62208 kb\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 393
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%run tmp/original_str_performance.py 5"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "method 5\n",
        "time 5.35268783569\n",
        "output size  477 kb\n",
        "process size 59916 kb\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 394
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%run tmp/original_str_performance.py 6"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "method 6\n",
        "time 1.88450813293\n",
        "output size  477 kb\n",
        "process size 59892 kb\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 395
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### xrange vs range\n",
      "\n",
      "- xrange\uac00 \uba54\ubaa8\ub9ac \uc801\uac8c \uc18c\ubaa8\n",
      "- python 3.0 \ubc84\uc804\uc5d0\uc11c\ub294 range\ub3c4 xrange\ub85c \ubcc0\uacbd\ub418\uc11c iterator\uac00 \ub428"
     ]
    }
   ],
   "metadata": {}
  }
 ]
}