commit lesson01 and lesson02

Student/tammyd_Py220/Py220_lesson01/Concept-1-Procedural-vs-Functional-Programming-A-Simple-Calculator (1).ipynb

@@ -0,0 +1,208 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Pure Function\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def m(n: int) -> int:\n",
+    "    return 2**n-1\n",
+    "\n",
+    "## This result depends only on the parameter, n. \n",
+    "## There are no changes to global variables and the function doesn't update any mutable data structures."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## A procedural approach!\n",
+    "\n",
+    "- Functions generally consist of multiple statements\n",
+    "  - Assignments\n",
+    "  - If-statements\n",
+    "  - While loops\n",
+    "  - Etc."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Welcome to the barely functional calculator!\n",
+      "Enter an integer: a\n",
+      "That is not an integer!\n",
+      "Enter an integer: a\n",
+      "That is not an integer!\n",
+      "Enter an integer: a\n",
+      "That is not an integer!\n",
+      "Enter an integer: 8\n",
+      "Enter an operator (+, -, *, or /): &\n",
+      "That is not an operator!\n",
+      "Enter an operator (+, -, *, or /): /\n",
+      "Enter an integer: 9\n",
+      "The result is: 0.8888888888888888\n"
+     ]
+    }
+   ],
+   "source": [
+    "OPERATORS = '+', '-', '*', '/'\n",
+    "\n",
+    "\n",
+    "def p_main():\n",
+    "    \n",
+    "    \"\"\"The main flow.\"\"\"\n",
+    "\n",
+    "    print('Welcome to the barely functional calculator!')\n",
+    "    number1 = p_get_number()\n",
+    "    operator = p_get_operator()\n",
+    "    number2 = p_get_number()\n",
+    "    result = p_calculate(number1, operator, number2)\n",
+    "    print('The result is: %s' % result)\n",
+    "\n",
+    "\n",
+    "def p_get_number():\n",
+    "    \n",
+    "    \"\"\"Reads an integer from the standard input and returns it.\n",
+    "    If a non-integer value is entered, a warning is printed,\n",
+    "    and a new value is read.\"\"\"\n",
+    "            \n",
+    "    while True:\n",
+    "        s = input('Enter an integer: ')\n",
+    "        try:\n",
+    "            return int(s)\n",
+    "        except ValueError:\n",
+    "            print('That is not an integer!')\n",
+    "            \n",
+    "\n",
+    "def p_get_operator():\n",
+    "    \n",
+    "    \"\"\"Reads an operator from the standard input and returns it.\n",
+    "    Valid operators are: +, -, *, and /. If an invalid operator\n",
+    "    is entered, a warning is printed, and a new value is read.\"\"\"    \n",
+    "    \n",
+    "    while True:\n",
+    "        s = input('Enter an operator (+, -, *, or /): ')\n",
+    "        if s in OPERATORS:\n",
+    "            return s\n",
+    "        print('That is not an operator!')\n",
+    "            \n",
+    "            \n",
+    "def p_calculate(number1, operator, number2):\n",
+    "    \n",
+    "    \"\"\"Performs a calculation with two numbers and an operator,\n",
+    "    and returns the result.\"\"\"\n",
+    "    \n",
+    "    if operator == '+':\n",
+    "        return number1 + number2\n",
+    "    if operator == '-':\n",
+    "        return number1 - number2\n",
+    "    if operator == '*':\n",
+    "        return number1 * number2\n",
+    "    if operator == '/':\n",
+    "        return number1 / number2\n",
+    "    raise Exception('Invalid operator!')\n",
+    "\n",
+    "    \n",
+    "p_main()\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## A functional approach!\n",
+    "\n",
+    "- Functions consist of only one expression\n",
+    "- How can we validate input? (One of the many things we will learn later!)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Enter and integer: 8\n",
+      "Enter an operator(+, -, *, /): *\n",
+      "Enter and integer: 8\n",
+      "The result is: 64\n"
+     ]
+    }
+   ],
+   "source": [
+    "OPERATORS = '+', '-', '*', '/'\n",
+    "\n",
+    "\n",
+    "def f_get_number():\n",
+    "    return int(input(\"Enter and integer: \"))\n",
+    "\n",
+    "\n",
+    "def f_get_operator():\n",
+    "    return input(\"Enter an operator(+, -, *, /): \")\n",
+    "\n",
+    "\n",
+    "def f_calculate(number1, operator, number2):\n",
+    "    return number1 + number2 if operator == \"+\"\\\n",
+    "    else number1 * number2 if operator == \"*\"\\\n",
+    "    else number1 - number2 if operator == '-'\\\n",
+    "    else number1 / number2 if operator == '/'\\\n",
+    "    else None\n",
+    "\n",
+    "def f_main():\n",
+    "    return f_calculate(\n",
+    "            f_get_number(),\n",
+    "            f_get_operator(),\n",
+    "            f_get_number()\n",
+    "            )\n",
+    "    \n",
+    "    \n",
+    "print('The result is: %s' % f_main())"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
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+   "language": "python",
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+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
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+   "nbconvert_exporter": "python",
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