aa

bb.ipynb

{
 "metadata": {
  "name": "map_loop2"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 3,
     "metadata": {},
     "source": [
      "Map vs For Loop"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "I've been looking at a lot of mapping functions today and I thought I would see how maps fare against a simple for loop."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "test=[]\n",
      "\n",
      "def tst(func):\n",
      "    global test\n",
      "    test+=[[func, func.__name__]]\n",
      "    return func\n",
      "\n",
      "@tst\n",
      "def convert_for1(data):\n",
      "    output = []\n",
      "    for line in data:\n",
      "        x,y = line.split(',')\n",
      "        output+=[[float(x),float(y)]]\n",
      "    return output\n",
      "\n",
      "@tst\n",
      "def convert_for2(data):\n",
      "    output = []\n",
      "    for line in data:\n",
      "        x,y = line.split(',')\n",
      "        output.append([float(x),float(y)])\n",
      "    return output\n",
      "\n",
      "@tst\n",
      "def convert_map(data):\n",
      "    return [list(map(float, x.split(','))) for x in data]\n",
      "\n",
      "@tst\n",
      "def convert_map2(data):\n",
      "    return [[i for i in map(float,x.split(','))] for x in data]\n",
      "\n",
      "@tst\n",
      "def convert_map3(data):\n",
      "    return [map(float, x.split(',')) for x in data]\n",
      "\n",
      "@tst\n",
      "def convert_map4(data):\n",
      "    return map(lambda line:map(float, line.split(',')), data)\n",
      "\n",
      "@tst\n",
      "def convert_map5(data):\n",
      "    return [[j for j in i] for i in map(lambda line:map(float, line.split(',')), data)]\n",
      "\n",
      "@tst\n",
      "def convert_compr(data):\n",
      "    return [[float(i), float(j)] for i,j in [k.split(',') for k in data]]\n",
      "\n",
      "@tst\n",
      "def convert_gener(data):\n",
      "    return [[float(i), float(j)] for i,j in (k.split(',') for k in data)]\n",
      "\n",
      "@tst\n",
      "def convert_list_comprehension(data):\n",
      "    \"\"\"This is the same as convert_map, just faster and more readable\"\"\"\n",
      "    return [[float(y) for y in x.split(',')] for x in data]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 388
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Well I have to admit that the code looks a *lot* cleaner using the mapping function."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "text = \"\"\" 1,2\n",
      "           2,3\n",
      "           3,4\n",
      "           5,6\n",
      "           7,8\"\"\"\n",
      "data = text.splitlines()\n",
      "data = ['0.1, 0.3', '0.4, 0.5', '0.7, 0.8', '0.3, 0.9', '0.9, 0.4', '1.0, 0.9', '0.0, 0.5', '0.1, 0.8', '0.9, 0.8', '0.8, 0.6']"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 389
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Checking to see that they return the same thing..."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "result=convert_for1(data)\n",
      "print(result)\n",
      "for i in test:\n",
      "    print(i[1], i[0](data)==result)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "[[0.1, 0.3], [0.4, 0.5], [0.7, 0.8], [0.3, 0.9], [0.9, 0.4], [1.0, 0.9], [0.0, 0.5], [0.1, 0.8], [0.9, 0.8], [0.8, 0.6]]\n",
        "('convert_for1', True)\n",
        "('convert_for2', True)\n",
        "('convert_map', True)\n",
        "('convert_map2', True)\n",
        "('convert_map3', True)\n",
        "('convert_map4', True)\n",
        "('convert_map5', True)\n",
        "('convert_compr', True)\n",
        "('convert_gener', True)\n",
        "('convert_list_comprehension', True)\n"
       ]
      }
     ],
     "prompt_number": 390
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Let check on the speed now.  Does few lines of code mean a faster function?"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import markdown\n",
      "class MD(str):\n",
      "    def _repr_html_(self):\n",
      "        return markdown.markdown(self)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 392
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for i in test:\n",
      "    print(i[1])\n",
      "    %timeit i[0](data)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "convert_for1\n",
        "100000 loops, best of 3: 7.7 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_for2\n",
        "100000 loops, best of 3: 7.24 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_map\n",
        "100000 loops, best of 3: 9.55 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_map2\n",
        "100000 loops, best of 3: 8.95 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_map3\n",
        "100000 loops, best of 3: 7.47 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_map4\n",
        "100000 loops, best of 3: 8.33 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_map5\n",
        "100000 loops, best of 3: 10.5 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_compr\n",
        "100000 loops, best of 3: 7.04 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_gener\n",
        "100000 loops, best of 3: 7.19 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "convert_list_comprehension\n",
        "100000 loops, best of 3: 7.12 us per loop"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n"
       ]
      }
     ],
     "prompt_number": 393
    }
   ],
   "metadata": {}
  }
 ]
}