python_basics_02_everything_class.ipynb

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      "Size of bool is 28 bytes\nSize of int is 28 bytes\nSize of float is 24 bytes\nSize of float32 is 28 bytes\nSize of empty string is 49 bytes\nSize of string 's' is 50 bytes\n"
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    "\"\"\"\n",
    "Everything is a class / object:\n",
    "    integers, floats, strings, bool\n",
    "    list, tuple, dictionary\n",
    "    class, function\n",
    "    libraries, packages\n",
    "\"\"\"\n",
    "\n",
    "\n",
    "class SubjectInfo(object):\n",
    "    # class variables\n",
    "    description = 'The University of Melbourne subjects'\n",
    "    \n",
    "    def __init__(self):\n",
    "        # instance variables\n",
    "        self.subject_ID = None\n",
    "        self.subject_name = None\n",
    "        self.lecture_name = None\n",
    "        self.tutor_name = None\n",
    "        self.student_names = None\n",
    "        self.num_staff = None\n",
    "        self.num_students = 0\n",
    "        \n",
    "    @staticmethod\n",
    "    def do_count(name):  # class methods\n",
    "        if isinstance(name, str):\n",
    "            return 1\n",
    "        elif isinstance(name, (list, tuple, dict)):\n",
    "            return len(name)\n",
    "        elif name is None:\n",
    "            return 0\n",
    "        else:\n",
    "            raise AttributeError('Name must be str, list, tuple or dictionary.')\n",
    "        \n",
    "    def get_num_students(self):  # class methods\n",
    "        self.num_students = self.do_count(self.student_names)\n",
    "        return self.num_students\n",
    "        \n",
    "        \n",
    "class AIMechatronics(SubjectInfo):\n",
    "    def __init__(self):\n",
    "        super().__init__()\n",
    "        self.subject_ID = 'MCEN90048'\n",
    "        self.subject_name = 'AI for Mechatronics'\n",
    "        self.workshop_attendances = None\n",
    "        self.spartan_support = True\n",
    "        \n",
    "\n",
    "class AdvancedSolidMechanics(SubjectInfo):\n",
    "    def __init__(self):\n",
    "        super().__init__()\n",
    "        self.subject_ID = 'MCEN90029'\n",
    "        self.subject_name = 'Advanced Solid Mechanics'\n",
    "        self.tutorials = None\n",
    "        self.lab_study = True\n"
   ]
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   "execution_count": 11,
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     "text": [
      "Size of bool is 28 bytes\nSize of int is 28 bytes\nSize of float is 24 bytes\nSize of float32 is 28 bytes\nSize of empty string is 49 bytes\nSize of string 's' is 50 bytes\n"
     ]
    }
   ],
   "source": [
    "my_subject = AIMechatronics()\n",
    "my_subject1 = AdvancedSolidMechanics()\n",
    "\n",
    "my_subject.tutor_name = 'Richard'\n",
    "my_subject.student_names = ['Olivia', 'Oliver', 'Amelia', 'Harry', \n",
    "                            'Isla', 'Jack']\n",
    "num_students = my_subject.get_num_students()\n",
    "print('Subject {} has {} students'.format(\n",
    "    my_subject.subject_ID + ' ' + my_subject.subject_name, \n",
    "    my_subject.num_students))\n",
    "print('Subject {} has {} students'.format(\n",
    "    my_subject1.subject_ID + ' ' + my_subject1.subject_name, \n",
    "    my_subject1.num_students))\n",
    "\n",
    "print(AIMechatronics.description)\n",
    "SubjectInfo.description = 'Mechanical Engineering subjects'\n",
    "print(my_subject.description)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
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   "outputs": [
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     "text": [
      "Size of bool is 28 bytes\nSize of int is 28 bytes\nSize of float is 24 bytes\nSize of empty string is 49 bytes\nSize of string 's' is 50 bytes\n"
     ]
    }
   ],
   "source": [
    "# basic data types \n",
    "# numbers: integer, float, bool\n",
    "import sys\n",
    "\n",
    "# sys.getsizeof gets the memory size in bytes\n",
    "print('Size of bool is {} bytes'.format(sys.getsizeof(True)))\n",
    "print('Size of int is {} bytes'.format(sys.getsizeof(32)))  # we often use integer8, integer32, integer64\n",
    "print('Size of float is {} bytes'.format(sys.getsizeof(32.0)))  # we will often use float32, float16\n",
    "print('Size of empty string is {} bytes'.format(sys.getsizeof('')))\n",
    "print(\"Size of string 's' is {} bytes\".format(sys.getsizeof('s')))\n"
   ]
  },
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   "cell_type": "code",
   "execution_count": 1,
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     "text": [
      "----list----\nSize of empty list is 64 bytes\nSize of one-element list is 72 bytes\n----tuple----\nSize of empty tuple is 48 bytes\nSize of two-element tuple is 64 bytes\n----dictionary----\nSize of empty dictionary is 240 bytes\nSize of two-key:value-pair dictionary is 240 bytes\n----set----\nSize of empty set is 224 bytes\nSize of two-element set is 224 bytes\n----numpy array----\nSize of empty array is 96 bytes\nSize of one-float array is 104 bytes\nSize of one-float32 array is 100 bytes\n"
     ]
    }
   ],
   "source": [
    "# list, tuple, dictionary, sets\n",
    "import sys\n",
    "import numpy as np\n",
    "\n",
    "print('----list----')\n",
    "print('Size of empty list is {} bytes'.format(sys.getsizeof([])))  # initialize empty list with square brackets\n",
    "print('Size of one-element list is {} bytes'.format(sys.getsizeof([2.0])))  # list, square bracket\n",
    "print('----tuple----')\n",
    "print('Size of empty tuple is {} bytes'.format(sys.getsizeof(())))  # initialize empty tuple with round bracket\n",
    "print('Size of two-element tuple is {} bytes'.format(sys.getsizeof((3.0, 2.0))))  # tuple, round bracket\n",
    "print('----dictionary----')\n",
    "print('Size of empty dictionary is {} bytes'.format(sys.getsizeof({})))  # initialize empty dictionary with braces or curly brackets\n",
    "print('Size of two-key:value-pair dictionary is {} bytes'.format(sys.getsizeof({'a': 3.0, 'b': 2.0})))  # dictionary initialized by key:value pair\n",
    "print('----set----')\n",
    "print('Size of empty set is {} bytes'.format(sys.getsizeof(set())))  # empty set, initialized by set()\n",
    "print('Size of two-element set is {} bytes'.format(sys.getsizeof({3.0, 2.0})))  # empty set, initialized by set()\n",
    "print('----numpy array----')\n",
    "print('Size of empty array is {} bytes'.format(sys.getsizeof(np.array([]))))  # numpy array, initialized by np.array\n",
    "print('Size of one-float array is {} bytes'.format(sys.getsizeof(np.array([3.0]))))\n",
    "print('Size of one-float32 array is {} bytes'.format(sys.getsizeof(np.array([3.0], dtype=np.float32))))\n"
   ]
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  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Size of function is 136 bytes\n"
     ]
    }
   ],
   "source": [
    "# functions\n",
    "import sys\n",
    "\n",
    "\n",
    "def manual_add(a, b):\n",
    "    return a+b\n",
    "\n",
    "\n",
    "print('Size of function is {} bytes'.format(sys.getsizeof(manual_add)))\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[3, 5, 7]\n[5, 7]\n"
     ]
    }
   ],
   "source": [
    "# list comprehension\n",
    "a = [2, 4, 6]\n",
    "b = [element+1 for element in a]\n",
    "print(b)\n",
    "c = [element+1 for element in a if element > 3]\n",
    "print(c)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[3, 5, 7]\n[5, 7]\n"
     ]
    }
   ],
   "source": [
    "# pass by reference\n",
    "import numpy as np\n",
    "\n",
    "a = np.array([2, 3, 4, 5])\n",
    "b = a + 10\n",
    "print(a)\n",
    "print(b)\n",
    "\n",
    "a = np.array([2, 3, 4, 5])\n",
    "c = a\n",
    "c[0] = 1\n",
    "print(a)\n",
    "print(c)\n",
    "\n",
    "a = np.array([2, 3, 4, 5])\n",
    "c = a.copy()\n",
    "c[0] = 1\n",
    "print(a)\n",
    "print(c)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": true
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "6\n"
     ]
    }
   ],
   "source": [
    "# lambda\n",
    "\n",
    "fun = lambda x: 2*x\n",
    "\n",
    "print(fun(3))\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
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   "outputs": [
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     "data": {
      "text/plain": [
       "317.36"
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     "execution_count": 24,
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   "source": [
    ""
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