{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {
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   },
   "source": [
    "## Introduction to Scientific Computing\n",
    "### Lecture 09: Object Oriented Programming and Class - 2\n",
    "#### J.R. Gladden, Spring 2018, Univ. of Mississippi"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "A **Super Class** is one that defines methods and attributes that can be shared across multiple other classes.  It is another method of making your code more modular.  Let's see an example of a *Shape()* superclass that incorporates multiple sub-classes such as Circle and Square.  The calcVolume method will be common to all sub-classes.  Note \"volume\" is computed here by simply extruding the shape into a 3rd dimension by a distance *h*.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "class Shapes():\n",
    "    def calcVolume(self,h):\n",
    "        area = self.calcArea()\n",
    "        #The next line allows the 'h' value to be accessed by the subclasses\n",
    "        self.h=h\n",
    "        return area*self.h"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "Now define ** sub-classes ** that are more specific to the type of shape.  These will have methods that are specific to the type of shape: calculating area and the perimeter.  Note how the Shapes super-class is now a \"parameter\" in the sub-class definitions.  These sub-classes with *inherit* the methods of the super-class."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "class MySquare(Shapes):\n",
    "    def __init__(self,s=1.0):\n",
    "        self.s = s\n",
    "        \n",
    "    def calcArea(self):\n",
    "        self.area = self.s**2    \n",
    "        return self.area\n",
    "    \n",
    "    def calcPerim(self):\n",
    "        return 4.0*self.s\n",
    "\n",
    "class MyCircle(Shapes):\n",
    "      \n",
    "    def __init__(self,r=1.0):\n",
    "        from math import pi\n",
    "        self.pi = pi\n",
    "        self.r = r\n",
    "        \n",
    "    def calcArea(self):    \n",
    "        self.area =  self.pi*self.r**2\n",
    "        return self.area\n",
    "    \n",
    "    def calcPerim(self):\n",
    "        return 2.0*self.pi*self.r"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "acircle = MyCircle(r=2.0)\n",
    "asquare = MySquare(s=1.5)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "12.566370614359172"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "acircle.calcPerim()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4.5"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "asquare.calcVolume(2.0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "---\n",
    "### Ball Class\n",
    "This is a slightly more complicated (and arguably useful) class is presented here.  We create a *Ball* class that computes and plots the trajectory of a ball thrown in the air."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "%matplotlib wx"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "class Ball:\n",
    "    \"\"\"\n",
    "    Ball class for a ball thrown in the air. JRG, Feb. 2012\n",
    "    Arguments:\n",
    "        y0: initial height\n",
    "        v0: initial velocity\n",
    "    Methods:\n",
    "        height(t): returns height at time t (t is float or array)\n",
    "        initParams(): returns tuple of initial parameters for a ball\n",
    "        maxHeight(t): returns the maximum height the ball reaches over a time interval t\n",
    "        showPlot(t): plots y(t)\n",
    "    Usage:\n",
    "        ball1=Ball(0.0,12.0)\n",
    "        t=linspace(0,5,100)\n",
    "        ball1.maxHeight(t)\n",
    "        ball1.showPlot(t)\n",
    "        NOTE: best to run in ipython with --pylab flag to show multiple trajectories\n",
    "    \"\"\"\n",
    "    \n",
    "    def __init__(self,y0,v0,balllabel='Ball'):\n",
    "        self.y0 = y0\n",
    "        self.v0 = v0\n",
    "        self.g=-9.81\n",
    "        self.ballLabel=balllabel\n",
    "        import numpy as np\n",
    "        import matplotlib.pyplot as plt\n",
    "    \t\n",
    "    def setLabel(self,label):\n",
    "    \tif type(label).__name__ == 'str': self.ballLabel = label\n",
    "    \t\n",
    "    def getLabel(self):\n",
    "    \treturn self.ballLabel\n",
    "    \t\n",
    "    def height(self,t):\n",
    "        if type(t).__name__ in ('ndarray', 'float', 'int'):\n",
    "        \treturn self.y0 + self.v0*t + 0.5*self.g*t**2\n",
    "        else: \n",
    "        \tprint 'An time array must be supplied to compute the maximum height'\n",
    "    \n",
    "    def initParams(self):\n",
    "        return self.y0,self.v0,self.g\n",
    "    \n",
    "    def maxHeight(self,t):\n",
    "        if type(t).__name__ in ('ndarray', 'float', 'int'): \n",
    "        \treturn max(self.height(t))\n",
    "        else: print 'An time array must be supplied to compute the maximum height'\n",
    "    \n",
    "    def showPlot(self,t):\n",
    "        plt.plot(t,self.height(t),'-',label=self.ballLabel)\n",
    "        plt.xlabel('Time')\n",
    "        plt.ylabel('Height')\n",
    "        plt.legend()\n",
    "        plt.show()\n",
    " "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "Here's how the ball class can be used.  Note multiple balls can be created."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "ball1=Ball(0.0,20.0)\n",
    "ball1.setLabel(\"Ball 1\")\n",
    "\n",
    "ball2=Ball(10.0,1.0)\n",
    "ball2.setLabel(\"Ball 2\")\n",
    "\n",
    "from numpy import linspace\n",
    "t=linspace(0,5,100)\n",
    "\n",
    "ball2Yvals = ball2.height(t)\n",
    "ball1.showPlot(t)\n",
    "ball2.showPlot(t)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "source": [
    "---\n",
    "### Polymorphism\n",
    "\n",
    "Finally we return to the Charge class to illustrate **polymorphism** by redefining the \"+\" operator to apply to 2 charge objects and return a new charge object with the sum of the masses and charges.  Note this is done with a \"magic\" method: __add__. Similar methods exist to redifine other operators."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "class Charge:\n",
    "    def __init__(self):\n",
    "        #Provide some default properties which can be changed later\n",
    "        #Everything in here will be executed when a \"Charge\" instance\n",
    "        #is created.\n",
    "        self.charge = 1.0\n",
    "        self.mass = 1.0\n",
    "    \n",
    "    def __add__(self,q2):\n",
    "        qsum=Charge()\n",
    "        qsum.charge=self.charge + q2.charge\n",
    "        qsum.mass = self.mass + q2.mass\n",
    "        return qsum\n",
    "        \n",
    "    def setCharge(self,value):\n",
    "        self.charge = value\n",
    "    \n",
    "    def getCharge(self):\n",
    "        return self.charge\n",
    "    \n",
    "    def getPolarity(self):\n",
    "        \n",
    "        if self.charge > 0.0: return '+'\n",
    "        elif self.charge == 0.0: return '0'\n",
    "        else: return '-'\n",
    "        \n",
    "    def switchPolarity(self):\n",
    "        self.charge = - self.charge\n",
    "    \n",
    "    def setMass(self,value):\n",
    "        self.mass = value\n",
    "        \n",
    "    def getMass(self):\n",
    "        return self.mass    "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "Here's an example of the usage:\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4.0"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "q1 = Charge()\n",
    "q2 = Charge()\n",
    "q2.setMass(3.0)\n",
    "q2.setCharge(-5.0)\n",
    "\n",
    "# q3 is a new charge object\n",
    "q3 = q1+q2\n",
    "\n",
    "q3.getCharge()\n",
    "q3.getMass()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "### Large Collections of objects\n",
    "Let's say we want to create and manipulate 100 Star objects.  We can create lists of instances and loop over those lists to change attributes, compute interactions, ...\n",
    "\n",
    "Each instance can be referenced by it's location in the list: "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 49,
   "metadata": {
    "collapsed": true,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "N=100\n",
    "stars = [ Star() for i in range(N)]    # This creates a list of 100 Stars()\n",
    "Ms= [ random.randint(100,1000) for i in range(N)]  # random masses between 100 and 1000"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 50,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1000000000.0"
      ]
     },
     "execution_count": 50,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "stars[4].getMass()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 51,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "for i in range(N):\n",
    "    stars[i].setMass(Ms[i])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 52,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "753"
      ]
     },
     "execution_count": 52,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "stars[4].getMass()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 57,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The mass of star   0 is: 578.0 Kg and density 1.380e-16 Kg/M^3\n",
      "The mass of star   1 is: 968.0 Kg and density 2.311e-16 Kg/M^3\n",
      "The mass of star   2 is: 220.0 Kg and density 5.252e-17 Kg/M^3\n",
      "The mass of star   3 is: 457.0 Kg and density 1.091e-16 Kg/M^3\n",
      "The mass of star   4 is: 753.0 Kg and density 1.798e-16 Kg/M^3\n",
      "The mass of star   5 is: 217.0 Kg and density 5.180e-17 Kg/M^3\n",
      "The mass of star   6 is: 241.0 Kg and density 5.753e-17 Kg/M^3\n",
      "The mass of star   7 is: 971.0 Kg and density 2.318e-16 Kg/M^3\n",
      "The mass of star   8 is: 638.0 Kg and density 1.523e-16 Kg/M^3\n",
      "The mass of star   9 is: 141.0 Kg and density 3.366e-17 Kg/M^3\n",
      "The mass of star  10 is: 512.0 Kg and density 1.222e-16 Kg/M^3\n",
      "The mass of star  11 is: 577.0 Kg and density 1.377e-16 Kg/M^3\n",
      "The mass of star  12 is: 618.0 Kg and density 1.475e-16 Kg/M^3\n",
      "The mass of star  13 is: 997.0 Kg and density 2.380e-16 Kg/M^3\n",
      "The mass of star  14 is: 566.0 Kg and density 1.351e-16 Kg/M^3\n",
      "The mass of star  15 is: 383.0 Kg and density 9.143e-17 Kg/M^3\n",
      "The mass of star  16 is: 462.0 Kg and density 1.103e-16 Kg/M^3\n",
      "The mass of star  17 is: 801.0 Kg and density 1.912e-16 Kg/M^3\n",
      "The mass of star  18 is: 459.0 Kg and density 1.096e-16 Kg/M^3\n",
      "The mass of star  19 is: 355.0 Kg and density 8.475e-17 Kg/M^3\n",
      "The mass of star  20 is: 657.0 Kg and density 1.568e-16 Kg/M^3\n",
      "The mass of star  21 is: 826.0 Kg and density 1.972e-16 Kg/M^3\n",
      "The mass of star  22 is: 346.0 Kg and density 8.260e-17 Kg/M^3\n",
      "The mass of star  23 is: 150.0 Kg and density 3.581e-17 Kg/M^3\n",
      "The mass of star  24 is: 353.0 Kg and density 8.427e-17 Kg/M^3\n",
      "The mass of star  25 is: 982.0 Kg and density 2.344e-16 Kg/M^3\n",
      "The mass of star  26 is: 962.0 Kg and density 2.297e-16 Kg/M^3\n",
      "The mass of star  27 is: 617.0 Kg and density 1.473e-16 Kg/M^3\n",
      "The mass of star  28 is: 550.0 Kg and density 1.313e-16 Kg/M^3\n",
      "The mass of star  29 is: 940.0 Kg and density 2.244e-16 Kg/M^3\n",
      "The mass of star  30 is: 697.0 Kg and density 1.664e-16 Kg/M^3\n",
      "The mass of star  31 is: 360.0 Kg and density 8.594e-17 Kg/M^3\n",
      "The mass of star  32 is: 354.0 Kg and density 8.451e-17 Kg/M^3\n",
      "The mass of star  33 is: 837.0 Kg and density 1.998e-16 Kg/M^3\n",
      "The mass of star  34 is: 392.0 Kg and density 9.358e-17 Kg/M^3\n",
      "The mass of star  35 is: 642.0 Kg and density 1.533e-16 Kg/M^3\n",
      "The mass of star  36 is: 189.0 Kg and density 4.512e-17 Kg/M^3\n",
      "The mass of star  37 is: 973.0 Kg and density 2.323e-16 Kg/M^3\n",
      "The mass of star  38 is: 597.0 Kg and density 1.425e-16 Kg/M^3\n",
      "The mass of star  39 is: 435.0 Kg and density 1.038e-16 Kg/M^3\n",
      "The mass of star  40 is: 166.0 Kg and density 3.963e-17 Kg/M^3\n",
      "The mass of star  41 is: 429.0 Kg and density 1.024e-16 Kg/M^3\n",
      "The mass of star  42 is: 723.0 Kg and density 1.726e-16 Kg/M^3\n",
      "The mass of star  43 is: 120.0 Kg and density 2.865e-17 Kg/M^3\n",
      "The mass of star  44 is: 620.0 Kg and density 1.480e-16 Kg/M^3\n",
      "The mass of star  45 is: 779.0 Kg and density 1.860e-16 Kg/M^3\n",
      "The mass of star  46 is: 664.0 Kg and density 1.585e-16 Kg/M^3\n",
      "The mass of star  47 is: 879.0 Kg and density 2.098e-16 Kg/M^3\n",
      "The mass of star  48 is: 774.0 Kg and density 1.848e-16 Kg/M^3\n",
      "The mass of star  49 is: 735.0 Kg and density 1.755e-16 Kg/M^3\n",
      "The mass of star  50 is: 207.0 Kg and density 4.942e-17 Kg/M^3\n",
      "The mass of star  51 is: 732.0 Kg and density 1.748e-16 Kg/M^3\n",
      "The mass of star  52 is: 351.0 Kg and density 8.380e-17 Kg/M^3\n",
      "The mass of star  53 is: 580.0 Kg and density 1.385e-16 Kg/M^3\n",
      "The mass of star  54 is: 335.0 Kg and density 7.998e-17 Kg/M^3\n",
      "The mass of star  55 is: 612.0 Kg and density 1.461e-16 Kg/M^3\n",
      "The mass of star  56 is: 913.0 Kg and density 2.180e-16 Kg/M^3\n",
      "The mass of star  57 is: 939.0 Kg and density 2.242e-16 Kg/M^3\n",
      "The mass of star  58 is: 527.0 Kg and density 1.258e-16 Kg/M^3\n",
      "The mass of star  59 is: 417.0 Kg and density 9.955e-17 Kg/M^3\n",
      "The mass of star  60 is: 306.0 Kg and density 7.305e-17 Kg/M^3\n",
      "The mass of star  61 is: 385.0 Kg and density 9.191e-17 Kg/M^3\n",
      "The mass of star  62 is: 441.0 Kg and density 1.053e-16 Kg/M^3\n",
      "The mass of star  63 is: 518.0 Kg and density 1.237e-16 Kg/M^3\n",
      "The mass of star  64 is: 513.0 Kg and density 1.225e-16 Kg/M^3\n",
      "The mass of star  65 is: 607.0 Kg and density 1.449e-16 Kg/M^3\n",
      "The mass of star  66 is: 157.0 Kg and density 3.748e-17 Kg/M^3\n",
      "The mass of star  67 is: 945.0 Kg and density 2.256e-16 Kg/M^3\n",
      "The mass of star  68 is: 473.0 Kg and density 1.129e-16 Kg/M^3\n",
      "The mass of star  69 is: 615.0 Kg and density 1.468e-16 Kg/M^3\n",
      "The mass of star  70 is: 550.0 Kg and density 1.313e-16 Kg/M^3\n",
      "The mass of star  71 is: 145.0 Kg and density 3.462e-17 Kg/M^3\n",
      "The mass of star  72 is: 438.0 Kg and density 1.046e-16 Kg/M^3\n",
      "The mass of star  73 is: 809.0 Kg and density 1.931e-16 Kg/M^3\n",
      "The mass of star  74 is: 736.0 Kg and density 1.757e-16 Kg/M^3\n",
      "The mass of star  75 is: 568.0 Kg and density 1.356e-16 Kg/M^3\n",
      "The mass of star  76 is: 143.0 Kg and density 3.414e-17 Kg/M^3\n",
      "The mass of star  77 is: 328.0 Kg and density 7.830e-17 Kg/M^3\n",
      "The mass of star  78 is: 898.0 Kg and density 2.144e-16 Kg/M^3\n",
      "The mass of star  79 is: 564.0 Kg and density 1.346e-16 Kg/M^3\n",
      "The mass of star  80 is: 605.0 Kg and density 1.444e-16 Kg/M^3\n",
      "The mass of star  81 is: 877.0 Kg and density 2.094e-16 Kg/M^3\n",
      "The mass of star  82 is: 237.0 Kg and density 5.658e-17 Kg/M^3\n",
      "The mass of star  83 is: 399.0 Kg and density 9.525e-17 Kg/M^3\n",
      "The mass of star  84 is: 500.0 Kg and density 1.194e-16 Kg/M^3\n",
      "The mass of star  85 is: 521.0 Kg and density 1.244e-16 Kg/M^3\n",
      "The mass of star  86 is: 702.0 Kg and density 1.676e-16 Kg/M^3\n",
      "The mass of star  87 is: 569.0 Kg and density 1.358e-16 Kg/M^3\n",
      "The mass of star  88 is: 216.0 Kg and density 5.157e-17 Kg/M^3\n",
      "The mass of star  89 is: 776.0 Kg and density 1.853e-16 Kg/M^3\n",
      "The mass of star  90 is: 966.0 Kg and density 2.306e-16 Kg/M^3\n",
      "The mass of star  91 is: 137.0 Kg and density 3.271e-17 Kg/M^3\n",
      "The mass of star  92 is: 361.0 Kg and density 8.618e-17 Kg/M^3\n",
      "The mass of star  93 is: 205.0 Kg and density 4.894e-17 Kg/M^3\n",
      "The mass of star  94 is: 989.0 Kg and density 2.361e-16 Kg/M^3\n",
      "The mass of star  95 is: 876.0 Kg and density 2.091e-16 Kg/M^3\n",
      "The mass of star  96 is: 999.0 Kg and density 2.385e-16 Kg/M^3\n",
      "The mass of star  97 is: 421.0 Kg and density 1.005e-16 Kg/M^3\n",
      "The mass of star  98 is: 774.0 Kg and density 1.848e-16 Kg/M^3\n",
      "The mass of star  99 is: 371.0 Kg and density 8.857e-17 Kg/M^3\n"
     ]
    }
   ],
   "source": [
    "# List all the masses for each star\n",
    "for i in range(N):\n",
    "    mass = stars[i].getMass()\n",
    "    rho = stars[i].calcDensity()\n",
    "    print(\"The mass of star %3i is: %2.1f Kg and density %2.3e Kg/M^3\"%(i,mass,rho))"
   ]
  },
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   "source": []
  }
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