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{
"metadata": {
"name": "ch11"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.1\nAdding an Assignment Operator to the Ratio Class\nHere is a class interface for the Ratio class, showing the default constructor, the copy constructor,\nand the assignment operator:\n'''\nclass Ratio:\n def __init__(self,n=None,d=None):\n if d==None:\n self.num = n.num\n self.den = n.den\n elif n==None:\n self.num = 0\n self.den = 1\n else:\n self.num = n\n self.den = d\n \n def equals(self):\n return self # retuns calling object.",
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 1
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.2 The Preferred Prototype for an Overloaded Assignment Operator\n'''\nclass Ratio:\n def __init__(self,n=None,d=None):\n pass\n \n def equals(self):\n pass\n",
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 2
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.3 Implementation of the Assignment Operator for the Ratio Class\n'''\nclass Ratio:\n def __init__(self,n=None,d=None):\n if d==None:\n self.num = n.num\n self.den = n.den\n elif n==None:\n self.num = 0\n self.den = 1\n else:\n self.num = n\n self.den = d\n \n\nz = Ratio(22,7)\ny = z\nx = z\n\nx = Ratio(22,7)\ny = Ratio(x)\nz = x\nw = x",
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 3
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.4\nmultiplication operator overload\n'''\n\nclass Ratio:\n def __init__(self,n=None,d=None):\n self.num = n\n self.den = d\n def __mul__(self,y):\n pass\n",
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 4
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.5 The Ratio Class with Assignment and Multiplication Operators\n'''\ndef gcd(m,n):\n # returns the greatest common divisor of m and n:\n if (m<n):\n m,n = n,m\n while (n>0):\n r = m % n\n m = n\n n = r\n return m\n\n\nclass Ratio:\n def __init__(self,n=None,d=None):\n self.num = n\n self.den = d\n self.reduce()\n def __mul__(self,y):\n z = Ratio(self.num * y.num, self.den * y.den)\n return z\n def print_(self):\n print self.num , '/', self.den\n \n def reduce(self):\n # enforce invariant(den > 0):\n if (self.num == 0 or self.den == 0):\n self.num = 0\n self.den = 1\n return\n if (self.den < 0):\n self.den *= -1\n self.num *= -1\n # enforce invariant(gcd(num,den) == 1):\n if (self.den == 1):\n return\n # it's already reduced\n sgn = 0\n if self.num < 0:\n sgn = -1\n else:\n sgn = 1\n g = gcd(sgn*self.num,self.den)\n self.num /= g\n self.den /= g\nx = Ratio(22,7)\ny = Ratio(-3,8)\nz = x\nz.print_()\nx = y*z\nx.print_()\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "22 / 7\n-33 / 28\n"
}
],
"prompt_number": 5
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.6 The Ratio Class with an Overloaded *= Operator\n'''\ndef gcd(m,n):\n # returns the greatest common divisor of m and n:\n if (m<n):\n m,n = n,m\n while (n>0):\n r = m % n\n m = n\n n = r\n return m\n\n\nclass Ratio:\n def __init__(self,n=None,d=None):\n self.num = n\n self.den = d\n self.reduce()\n def __imul__(self,y):\n self.num = self.num * y.num\n self.den = self.den * y.den\n def print_(self):\n print self.num , '/', self.den",
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 6
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.7 Overloading the Equality Operator == in the Ratio Class\n'''\n\nclass Ratio:\n def __init__(self,n=None,d=None):\n self.num = n\n self.den = d\n self.reduce()\n def __imul__(self,y):\n self.num = self.num * y.num\n self.den = self.den * y.den\n def __eq__(self,y):\n return (x.num * y.den == y.num * x.den)\n def print_(self):\n print self.num , '/', self.den\n\n",
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 7
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.8 \nPython does not use << operator for printing. So here we are just declaring function name as print_.\n'''\n\nclass Ratio:\n def __init__(self,n=None,d=None):\n self.num = n\n self.den = d\n def __imul__(self,y):\n self.num = self.num * y.num\n self.den = self.den * y.den\n def __eq__(self,y):\n return (x.num * y.den == y.num * x.den)\n def print_(self):\n print self.num , '/', self.den\n\n\nx = Ratio(22,7)\ny = Ratio(-3,8)\nx.print_() , y.print_()\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "22 / 7\n-3 / 8\n"
},
{
"metadata": {},
"output_type": "pyout",
"prompt_number": 8,
"text": "(None, None)"
}
],
"prompt_number": 8
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.9 \nPython does not have >> for input. so we will use input function.\n'''\ndef gcd(m,n):\n # returns the greatest common divisor of m and n:\n if (m<n):\n m,n = n,m\n while (n>0):\n r = m % n\n m = n\n n = r\n return m\nclass Ratio:\n def __init__(self,n=0,d=1):\n self.num = n\n self.den = d\n self.reduce()\n def __mul__(self,y):\n z = Ratio(self.num * y.num, self.den * y.den)\n return z\n def print_(self):\n print self.num , '/', self.den\n \n def input(self):\n self.num = int(raw_input('Numerator : '))\n self.den = int(raw_input('Denominator : '))\n self.reduce()\n def reduce(self):\n # enforce invariant(den > 0):\n if (self.num == 0 or self.den == 0):\n self.num = 0\n self.den = 1\n return\n if (self.den < 0):\n self.den *= -1\n self.num *= -1\n # enforce invariant(gcd(num,den) == 1):\n if (self.den == 1):\n return\n # it's already reduced\n sgn = 0\n if self.num < 0:\n sgn = -1\n else:\n sgn = 1\n g = gcd(sgn*self.num,self.den)\n self.num /= g\n self.den /= g\n\n\nx = Ratio()\ny = Ratio()\nx.input()\ny.input()\nx.print_()\ny.print_()\n",
"language": "python",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": "Numerator : -10\n"
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": "Denominator : -24\n"
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": "Numerator : 36\n"
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": "Denominator : -20\n"
},
{
"output_type": "stream",
"stream": "stdout",
"text": "5 / 12\n-9 / 5\n"
}
],
"prompt_number": 1
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.10\nAdding a Conversion Operator to the Ratio Class\n'''\ndef gcd(m,n):\n # returns the greatest common divisor of m and n:\n if (m<n):\n m,n = n,m\n while (n>0):\n r = m % n\n m = n\n n = r\n return m\nclass Ratio:\n def __init__(self,n=0,d=1):\n self.num = n\n self.den = d\n self.reduce()\n def __mul__(self,y):\n z = Ratio(self.num * y.num, self.den * y.den)\n return z\n def print_(self):\n print self.num , '/', self.den\n \n def input(self):\n self.num = int(raw_input('Numerator : '))\n self.den = int(raw_input('Denominator : '))\n self.reduce()\n def __float__(self):\n return float(self.num)/self.den\n def reduce(self):\n # enforce invariant(den > 0):\n if (self.num == 0 or self.den == 0):\n self.num = 0\n self.den = 1\n return\n if (self.den < 0):\n self.den *= -1\n self.num *= -1\n # enforce invariant(gcd(num,den) == 1):\n if (self.den == 1):\n return\n # it's already reduced\n sgn = 0\n if self.num < 0:\n sgn = -1\n else:\n sgn = 15.py\n g = gcd(sgn*self.num,self.den)\n self.num /= g\n self.den /= g\n\nx = Ratio(-5,8)\nprint \"x = \" , \nx.print_() \nprint \", float(x) = \" , float(x) \nP = Ratio(22,7)\nPI = float(P)\nprint \"P = \" ,\nP.print_() \nprint \", PI = \" , PI\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "x = -5 / 8\n, float(x) = -0.625\nP = 22 / 7\n, PI = 3.14285714286\n"
}
],
"prompt_number": 3
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.11 Adding a Pre-Increment Operator to the Ratio Class\n'''\ndef gcd(m,n):\n # returns the greatest common divisor of m and n:\n if (m<n):\n m,n = n,m\n while (n>0):\n r = m % n\n m = n\n n = r\n return m\nclass Ratio:\n def __init__(self,n=0,d=1):\n self.num = n\n self.den = d\n self.reduce()\n def __mul__(self,y):\n z = Ratio(self.num * y.num, self.den * y.den)\n return z\n def print_(self):\n print self.num , '/', self.den\n \n def __iadd__(self,n):\n self.num += self.den\n return self\n def reduce(self):\n # enforce invariant(den > 0):\n if (self.num == 0 or self.den == 0):\n self.num = 0\n self.den = 1\n return\n if (self.den < 0):\n self.den *= -1\n self.num *= -1\n # enforce invariant(gcd(num,den) == 1):\n if (self.den == 1):\n return\n # it's already reduced\n sgn = 0\n if self.num < 0:\n sgn = -1\n else:\n sgn = 1\n g = gcd(sgn*self.num,self.den)\n self.num /= g\n self.den /= g\n\nx = Ratio(22,7)\nx += 1\ny = x\nprint \"y = \" ,\ny.print_()\nprint \", x = \",\nx.print_()\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "y = 29 / 7\n, x = 29 / 7\n"
}
],
"prompt_number": 5
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.12 Adding a Post-Increment Operator to the Ratio Class\n'''\ndef gcd(m,n):\n # returns the greatest common divisor of m and n:\n if (m<n):\n m,n = n,m\n while (n>0):\n r = m % n\n m = n\n n = r\n return m\nclass Ratio:\n def __init__(self,n=0,d=1):\n self.num = n\n self.den = d\n self.reduce()\n def __mul__(self,y):\n z = Ratio(self.num * y.num, self.den * y.den)\n return z\n def print_(self):\n print self.num , '/', self.den\n \n def __iadd__(self,n):\n self.num += self.den\n return self\n def reduce(self):\n # enforce invariant(den > 0):\n if (self.num == 0 or self.den == 0):\n self.num = 0\n self.den = 1\n return\n if (self.den < 0):\n self.den *= -1\n self.num *= -1\n # enforce invariant(gcd(num,den) == 1):\n if (self.den == 1):\n return\n # it's already reduced\n sgn = 0\n if self.num < 0:\n sgn = -1\n else:\n sgn = 1\n g = gcd(sgn*self.num,self.den)\n self.num /= g\n self.den /= g\n\nx = Ratio(22,7)\ny = Ratio(x.num,x.den)\nx += 1\nprint \"y = \" ,\ny.print_()\nprint \", x = \",\nx.print_()\n\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "y = 22 / 7\n, x = 29 / 7\n"
}
],
"prompt_number": 9
},
{
"cell_type": "code",
"collapsed": false,
"input": "'''\nEXAMPLE 11.13\nAdding a Subscript Operator to the Ratio Class\n'''\ndef gcd(m,n):\n # returns the greatest common divisor of m and n:\n if (m<n):\n m,n = n,m\n while (n>0):\n r = m % n\n m = n\n n = r\n return m\nclass Ratio:\n def __init__(self,n=0,d=1):\n self.num = n\n self.den = d\n self.reduce()\n def __mul__(self,y):\n z = Ratio(self.num * y.num, self.den * y.den)\n return z\n def print_(self):\n print self.num , '/', self.den\n \n def __getitem__(self,k):\n if k == 1:\n return self.num\n else:\n return self.den\n def reduce(self):\n # enforce invariant(den > 0):\n if (self.num == 0 or self.den == 0):\n self.num = 0\n self.den = 1\n return\n if (self.den < 0):\n self.den *= -1\n self.num *= -1\n # enforce invariant(gcd(num,den) == 1):\n if (self.den == 1):\n return\n # it's already reduced\n sgn = 0\n if self.num < 0:\n sgn = -1\n else:\n sgn = 1\n g = gcd(sgn*self.num,self.den)\n self.num /= g\n self.den /= g\n\nx = Ratio(22,7)\nprint \"x = \" ,\nx.print_()\nprint \"x[1] = \" , x[1] , \", x[2] = \" , x[2]\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "x = 22 / 7\nx[1] = 22 , x[2] = 7\n"
}
],
"prompt_number": 7
},
{
"cell_type": "code",
"collapsed": false,
"input": "",
"language": "python",
"metadata": {},
"outputs": []
}
],
"metadata": {}
}
]
}
|
