{
 "metadata": {
  "name": "matlab_vs_python"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Requirements\n",
      "------------\n",
      "\n",
      "This notebook requires oct2py and octave\n",
      "\n"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%load_ext octavemagic\n",
      "import numpy as np # by convention"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "We can now type matlab (octave) commands into the notebook"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%%octave\n",
      "a = rand(4,8);"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# We could this in python like this\n",
      "# notice the first difference: namespaces\n",
      "# The python functions are not stored in the general namespace \n",
      "# The rand function is stored in the numpy.random package.\n",
      "# This keeps the environment cleaner\n",
      "\n",
      "np.random.rand(4,8)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Let's get the octave variable into python\n",
      "%octave_pull a"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# These should be the same now\n",
      "print(a)\n",
      "%octave a"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Introspection\n",
      "--------------\n",
      "\n",
      "Ok now let's get to work\n",
      "Let's start with some simple introspection"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# shape and size\n",
      "print('rank'.center(20, '*'))\n",
      "%octave disp(ndims(a))\n",
      "print(a.ndim)\n",
      "print('type'.center(20, '*'))\n",
      "%octave disp(class(a))\n",
      "print(a.dtype)\n",
      "print('shape'.center(20, '*'))\n",
      "%octave disp(size(a))\n",
      "print(a.shape)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Get a list of variables and check if a is in there.\n",
      "print('a' in dir())\n",
      "%octave who a"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# What can we do with a, only show the last 10\n",
      "dir(a)[-10:]\n",
      "# no equivalent in matlab"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Indexing\n",
      "---------"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# get the first element\n",
      "%octave a(1)\n",
      "a[0,0]\n",
      "# Two differences here:\n",
      "# - indexing a matlab 2d array with 1 value gives 1 value\n",
      "# - indexing a python 2d array with 1 value gives 1 row\n",
      "\n",
      "# - python starts counting at 0\n",
      "# - matlab starts counting at 1\n",
      "# http://www.cs.utexas.edu/users/EWD/ewd08xx/EWD831.PDF"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# get the first row\n",
      "% octave a(1,:)\n",
      "a[0,:]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# get the first column\n",
      "%octave a(:,1)\n",
      "a[:,0]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": "*"
    }
   ],
   "metadata": {}
  }
 ]
}