Functions in Python #4.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# [Amin M. Boulouma Blog](https://amboulouma.com)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Functions in Python #4"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "> [Reminder] 🔔\n",
    "- Help the creator channel reach 20k subscribers. He will keep uploading quality content for you: [Amin M. Boulouma Channel](https://www.youtube.com/channel/UCOZbokHO727qeStxeYSKMUQ?sub_confirmation=1)\n",
    "- This tutorial is best understood following the video playlist: [Python Ultimate Tutorial [Official Documentation]](https://www.youtube.com/watch?v=vQqisFjAnsE&list=PLpMTHmi814W0nSToTOC0Q18kREOjcJspW&index=1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Hosted by Amin M. Boulouma, contact and questions: [amine.boulouma.com](https://amine.boulouma.com)\n",
    "- Python tutorial made simple: https://youtu.be/vQqisFjAnsE\n",
    "- Source code: https://amboulouma.com/python-tutorial\n",
    "- Github: https://github.com/amboulouma/python-ultimate-tutorial"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Change theme of Jupyter Notebook:\n",
    "\n",
    "```!pip install jupyterthemes```\n",
    "\n",
    "```!jt -t monokai```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Defining functions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "def fib(n):    # write Fibonacci series up to n\n",
    "    \"\"\"Print a Fibonacci series up to n.\"\"\"\n",
    "    a, b, count = 0, 1, 0\n",
    "    while count < n:\n",
    "        print(a, end=' ')\n",
    "        a, b = b, a+b\n",
    "        count += 1 \n",
    "    print()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 10946 17711 28657 46368 75025 121393 196418 317811 514229 832040 1346269 2178309 3524578 5702887 9227465 14930352 24157817 39088169 63245986 102334155 165580141 267914296 433494437 701408733 1134903170 1836311903 2971215073 4807526976 7778742049 12586269025 20365011074 32951280099 53316291173 86267571272 139583862445 225851433717 365435296162 591286729879 956722026041 1548008755920 2504730781961 4052739537881 6557470319842 10610209857723 17167680177565 27777890035288 44945570212853 72723460248141 117669030460994 190392490709135 308061521170129 498454011879264 806515533049393 1304969544928657 2111485077978050 3416454622906707 5527939700884757 8944394323791464 14472334024676221 23416728348467685 37889062373143906 61305790721611591 99194853094755497 160500643816367088 259695496911122585 420196140727489673 679891637638612258 1100087778366101931 1779979416004714189 2880067194370816120 4660046610375530309 7540113804746346429 12200160415121876738 19740274219868223167 31940434634990099905 51680708854858323072 83621143489848422977 135301852344706746049 218922995834555169026 \n"
     ]
    }
   ],
   "source": [
    "fib(100)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<function __main__.fib(n)>"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fib"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 10946 17711 28657 46368 75025 121393 196418 317811 514229 832040 1346269 2178309 3524578 5702887 9227465 14930352 24157817 39088169 63245986 102334155 165580141 267914296 433494437 701408733 1134903170 1836311903 2971215073 4807526976 7778742049 12586269025 20365011074 32951280099 53316291173 86267571272 139583862445 225851433717 365435296162 591286729879 956722026041 1548008755920 2504730781961 4052739537881 6557470319842 10610209857723 17167680177565 27777890035288 44945570212853 72723460248141 117669030460994 190392490709135 308061521170129 498454011879264 806515533049393 1304969544928657 2111485077978050 3416454622906707 5527939700884757 8944394323791464 14472334024676221 23416728348467685 37889062373143906 61305790721611591 99194853094755497 160500643816367088 259695496911122585 420196140727489673 679891637638612258 1100087778366101931 1779979416004714189 2880067194370816120 4660046610375530309 7540113804746346429 12200160415121876738 19740274219868223167 31940434634990099905 51680708854858323072 83621143489848422977 135301852344706746049 218922995834555169026 \n"
     ]
    }
   ],
   "source": [
    "f = fib\n",
    "f(100)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n"
     ]
    }
   ],
   "source": [
    "fib(0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "None\n"
     ]
    }
   ],
   "source": [
    "print(fib(0))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [],
   "source": [
    "def fib2(n):  # return Fibonacci series up to n\n",
    "    \"\"\"Return a list containing the Fibonacci series up to n.\"\"\"\n",
    "    result = []\n",
    "    a, b = 0, 1\n",
    "    while a < n:\n",
    "        result.append(a)    # see below\n",
    "        a, b = b, a+b\n",
    "    return result"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "f100 = fib2(100)    # call it\n",
    "f100                # write the result"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Default Argument Values"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [],
   "source": [
    "def ask_ok(prompt, retries=4, reminder='Please try again!'):\n",
    "    while True:\n",
    "        ok = input(prompt)\n",
    "        if ok in ('y', 'ye', 'yes'):\n",
    "            return True\n",
    "        if ok in ('n', 'no', 'nop', 'nope'):\n",
    "            return False\n",
    "        retries = retries - 1\n",
    "        if retries < 0:\n",
    "            raise ValueError('invalid user response')\n",
    "        print(reminder)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Do you really want to quit?no\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ask_ok('Do you really want to quit?')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "OK to overwrite the file?a\n",
      "Please try again!\n",
      "OK to overwrite the file?a\n",
      "Please try again!\n",
      "OK to overwrite the file?a\n"
     ]
    },
    {
     "ename": "ValueError",
     "evalue": "invalid user response",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mValueError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-19-de1842508d82>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mask_ok\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'OK to overwrite the file?'\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;32m<ipython-input-15-16d7c37266ff>\u001b[0m in \u001b[0;36mask_ok\u001b[0;34m(prompt, retries, reminder)\u001b[0m\n\u001b[1;32m      8\u001b[0m         \u001b[0mretries\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mretries\u001b[0m \u001b[0;34m-\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      9\u001b[0m         \u001b[0;32mif\u001b[0m \u001b[0mretries\u001b[0m \u001b[0;34m<\u001b[0m \u001b[0;36m0\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 10\u001b[0;31m             \u001b[0;32mraise\u001b[0m \u001b[0mValueError\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'invalid user response'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m     11\u001b[0m         \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mreminder\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mValueError\u001b[0m: invalid user response"
     ]
    }
   ],
   "source": [
    "ask_ok('OK to overwrite the file?', 2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "OK to overwrite the file?a\n",
      "Come on, only yes or no!\n",
      "OK to overwrite the file?Yes\n",
      "Come on, only yes or no!\n",
      "OK to overwrite the file?yes\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ask_ok('OK to overwrite the file?', 2, 'Come on, only yes or no!')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "5\n"
     ]
    }
   ],
   "source": [
    "i = 5\n",
    "\n",
    "def f(arg=i):\n",
    "    print(arg)\n",
    "\n",
    "i = 6\n",
    "\n",
    "f()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1]\n",
      "[1, 2]\n",
      "[1, 2, 3]\n"
     ]
    }
   ],
   "source": [
    "def f(a, L=[]):\n",
    "    L.append(a)\n",
    "    return L\n",
    "\n",
    "print(f(1))\n",
    "print(f(2))\n",
    "print(f(3))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {},
   "outputs": [],
   "source": [
    "def f(a, L=None):\n",
    "    if L is None:\n",
    "        L = []\n",
    "    L.append(a)\n",
    "    return L"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[2, 3, 1]\n",
      "[2]\n",
      "[3]\n"
     ]
    }
   ],
   "source": [
    "print(f(1, [2,3]))\n",
    "print(f(2))\n",
    "print(f(3))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Keyword Arguments"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 38,
   "metadata": {},
   "outputs": [],
   "source": [
    "def parrot(voltage, state='a stiff', action='voom', type='Norwegian Blue'):\n",
    "    print(\"-- This parrot wouldn't\", action, end=' ')\n",
    "    print(\"if you put\", voltage, \"volts through it.\")\n",
    "    print(\"-- Lovely plumage, the\", type)\n",
    "    print(\"-- It's\", state, \"!\\n\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 39,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "-- This parrot wouldn't voom if you put 1000 volts through it.\n",
      "-- Lovely plumage, the Norwegian Blue\n",
      "-- It's a stiff !\n",
      "\n",
      "-- This parrot wouldn't voom if you put 1000 volts through it.\n",
      "-- Lovely plumage, the Norwegian Blue\n",
      "-- It's a stiff !\n",
      "\n",
      "-- This parrot wouldn't VOOOOOM if you put 1000000 volts through it.\n",
      "-- Lovely plumage, the Norwegian Blue\n",
      "-- It's a stiff !\n",
      "\n",
      "-- This parrot wouldn't VOOOOOM if you put 1000000 volts through it.\n",
      "-- Lovely plumage, the Norwegian Blue\n",
      "-- It's a stiff !\n",
      "\n",
      "-- This parrot wouldn't jump if you put a million volts through it.\n",
      "-- Lovely plumage, the Norwegian Blue\n",
      "-- It's bereft of life !\n",
      "\n",
      "-- This parrot wouldn't voom if you put a thousand volts through it.\n",
      "-- Lovely plumage, the Norwegian Blue\n",
      "-- It's pushing up the daisies !\n",
      "\n"
     ]
    }
   ],
   "source": [
    "parrot(1000)                                          # 1 positional argument\n",
    "parrot(voltage=1000)                                  # 1 keyword argument\n",
    "parrot(voltage=1000000, action='VOOOOOM')             # 2 keyword arguments\n",
    "parrot(action='VOOOOOM', voltage=1000000)             # 2 keyword arguments\n",
    "parrot('a million', 'bereft of life', 'jump')         # 3 positional arguments\n",
    "parrot('a thousand', state='pushing up the daisies')  # 1 positional, 1 keyword"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 40,
   "metadata": {
    "scrolled": false
   },
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "parrot() missing 1 required positional argument: 'voltage'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-40-9db1978cc13c>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mparrot\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m                     \u001b[0;31m# required argument missing\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: parrot() missing 1 required positional argument: 'voltage'"
     ]
    }
   ],
   "source": [
    "parrot()                     # required argument missing"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 41,
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "positional argument follows keyword argument (<ipython-input-41-b18b24da62fc>, line 1)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-41-b18b24da62fc>\"\u001b[0;36m, line \u001b[0;32m1\u001b[0m\n\u001b[0;31m    parrot(voltage=5.0, 'dead')  # non-keyword argument after a keyword argument\u001b[0m\n\u001b[0m                        ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m positional argument follows keyword argument\n"
     ]
    }
   ],
   "source": [
    "parrot(voltage=5.0, 'dead')  # non-keyword argument after a keyword argument"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "parrot() got multiple values for argument 'voltage'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-42-be58d87c4290>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mparrot\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m110\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mvoltage\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m220\u001b[0m\u001b[0;34m)\u001b[0m     \u001b[0;31m# duplicate value for the same argument\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: parrot() got multiple values for argument 'voltage'"
     ]
    }
   ],
   "source": [
    "parrot(110, voltage=220)     # duplicate value for the same argument"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 43,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "parrot() got an unexpected keyword argument 'actor'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-43-a52dad5fe6e7>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mparrot\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mactor\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;34m'John Cleese'\u001b[0m\u001b[0;34m)\u001b[0m  \u001b[0;31m# unknown keyword argument\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: parrot() got an unexpected keyword argument 'actor'"
     ]
    }
   ],
   "source": [
    "parrot(actor='John Cleese')  # unknown keyword argument"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "function() got multiple values for argument 'a'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-44-0658d145b8a6>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      2\u001b[0m     \u001b[0;32mpass\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      3\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 4\u001b[0;31m \u001b[0mfunction\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m0\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0ma\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m0\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: function() got multiple values for argument 'a'"
     ]
    }
   ],
   "source": [
    "def function(a):\n",
    "    pass\n",
    "\n",
    "function(0, a=0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 50,
   "metadata": {},
   "outputs": [],
   "source": [
    "def cheeseshop(kind, *arguments, **keywords):\n",
    "    print(\"-- Do you have any\", kind, \"?\")\n",
    "    print(\"-- I'm sorry, we're all out of\", kind)\n",
    "    print(arguments)\n",
    "    for arg in arguments:\n",
    "        print(arg)\n",
    "    print(\"-\" * 40)\n",
    "    print(keywords)\n",
    "    for kw in keywords:\n",
    "        print(kw, \":\", keywords[kw])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 51,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "-- Do you have any Limburger ?\n",
      "-- I'm sorry, we're all out of Limburger\n",
      "(\"It's very runny, sir.\", \"It's really very, VERY runny, sir.\", 13)\n",
      "It's very runny, sir.\n",
      "It's really very, VERY runny, sir.\n",
      "13\n",
      "----------------------------------------\n",
      "{'shopkeeper': 'Michael Palin', 'client': 'John Cleese', 'sketch': 'Cheese Shop Sketch'}\n",
      "shopkeeper : Michael Palin\n",
      "client : John Cleese\n",
      "sketch : Cheese Shop Sketch\n"
     ]
    }
   ],
   "source": [
    "cheeseshop(\"Limburger\", \"It's very runny, sir.\",\n",
    "           \"It's really very, VERY runny, sir.\", \n",
    "           13,\n",
    "           shopkeeper=\"Michael Palin\",\n",
    "           client=\"John Cleese\",\n",
    "           sketch=\"Cheese Shop Sketch\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Special parameters"
   ]
  },
  {
   "cell_type": "raw",
   "metadata": {},
   "source": [
    "def f(pos1, pos2, /, pos_or_kwd, *, kwd1, kwd2):\n",
    "      -----------    ----------     ----------\n",
    "        |             |                  |\n",
    "        |        Positional or keyword   |\n",
    "        |                                - Keyword only\n",
    "         -- Positional only"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 52,
   "metadata": {},
   "outputs": [],
   "source": [
    "def standard_arg(arg):\n",
    "    print(arg)\n",
    "\n",
    "def pos_only_arg(arg, /):\n",
    "    print(arg)\n",
    "\n",
    "def kwd_only_arg(*, arg):\n",
    "    print(arg)\n",
    "\n",
    "def combined_example(pos_only, /, standard, *, kwd_only):\n",
    "    print(pos_only, standard, kwd_only)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 53,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2\n"
     ]
    }
   ],
   "source": [
    "standard_arg(2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2\n"
     ]
    }
   ],
   "source": [
    "standard_arg(arg=2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 55,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n"
     ]
    }
   ],
   "source": [
    "pos_only_arg(1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 56,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "pos_only_arg() got some positional-only arguments passed as keyword arguments: 'arg'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-56-434db44f4ff9>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mpos_only_arg\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0marg\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: pos_only_arg() got some positional-only arguments passed as keyword arguments: 'arg'"
     ]
    }
   ],
   "source": [
    "pos_only_arg(arg=1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 57,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "kwd_only_arg() takes 0 positional arguments but 1 was given",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-57-896c53ef896c>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mkwd_only_arg\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m3\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: kwd_only_arg() takes 0 positional arguments but 1 was given"
     ]
    }
   ],
   "source": [
    "kwd_only_arg(3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 58,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3\n"
     ]
    }
   ],
   "source": [
    "kwd_only_arg(arg=3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 59,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "combined_example() takes 2 positional arguments but 3 were given",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-59-037a05a37207>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mcombined_example\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m3\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: combined_example() takes 2 positional arguments but 3 were given"
     ]
    }
   ],
   "source": [
    "combined_example(1, 2, 3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 60,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1 2 3\n"
     ]
    }
   ],
   "source": [
    "combined_example(1, 2, kwd_only=3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 61,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1 2 3\n"
     ]
    }
   ],
   "source": [
    "combined_example(1, standard=2, kwd_only=3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 62,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "combined_example() got some positional-only arguments passed as keyword arguments: 'pos_only'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-62-a0fe0f8338e9>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mcombined_example\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mpos_only\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mstandard\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m2\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mkwd_only\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m3\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: combined_example() got some positional-only arguments passed as keyword arguments: 'pos_only'"
     ]
    }
   ],
   "source": [
    "combined_example(pos_only=1, standard=2, kwd_only=3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 63,
   "metadata": {},
   "outputs": [],
   "source": [
    "def foo(name, **kwds):\n",
    "    return 'name' in kwds"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 64,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "foo() got multiple values for argument 'name'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m-------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0mTraceback (most recent call last)",
      "\u001b[0;32m<ipython-input-64-1e719af70668>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mfoo\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m**\u001b[0m\u001b[0;34m{\u001b[0m\u001b[0;34m'name'\u001b[0m\u001b[0;34m:\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m}\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: foo() got multiple values for argument 'name'"
     ]
    }
   ],
   "source": [
    "foo(1, **{'name': 2})"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 65,
   "metadata": {},
   "outputs": [],
   "source": [
    "def foo(name, /, **kwds):\n",
    "    return 'name' in kwds"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 66,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 66,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "foo(1, **{'name': 2})"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Arbitrary Argument Lists"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 67,
   "metadata": {},
   "outputs": [],
   "source": [
    "def concat(*args, sep=\"/\"):\n",
    "    return sep.join(args)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 68,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'earth/mars/venus'"
      ]
     },
     "execution_count": 68,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "concat(\"earth\", \"mars\", \"venus\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 69,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'earth mars venus'"
      ]
     },
     "execution_count": 69,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "concat(\"earth\", \"mars\", \"venus\", sep=\" \")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Unpacking Argument Lists"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 70,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[3, 4, 5]"
      ]
     },
     "execution_count": 70,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "list(range(3, 6)) "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 71,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[3, 4, 5]"
      ]
     },
     "execution_count": 71,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "args = [3, 6]\n",
    "list(range(*args))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Lambda Expressions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 76,
   "metadata": {},
   "outputs": [],
   "source": [
    "def make_incrementor(n):\n",
    "    return lambda x: x + n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 77,
   "metadata": {},
   "outputs": [],
   "source": [
    "f = make_incrementor(42)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 78,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "42"
      ]
     },
     "execution_count": 78,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "f(0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 79,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "43"
      ]
     },
     "execution_count": 79,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "f(1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 81,
   "metadata": {},
   "outputs": [],
   "source": [
    "data = list(range(5))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 85,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[16, 25, 36, 49, 64]"
      ]
     },
     "execution_count": 85,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "list(map(lambda x: (x + max(data))**2, data))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 86,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[(4, 'four'), (1, 'one'), (3, 'three'), (2, 'two')]"
      ]
     },
     "execution_count": 86,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four'), \n",
    "         (1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]\n",
    "pairs.sort(key=lambda pair: pair[1])\n",
    "pairs"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Documentation Strings"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 92,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Sum function of multiple arguments\n",
      "    *args    arguments to unpack in the function\n",
      "    \n"
     ]
    }
   ],
   "source": [
    "def sum_(*args):\n",
    "    \"\"\"Sum function of multiple arguments\n",
    "    *args    arguments to unpack in the function\n",
    "    \"\"\"\n",
    "    return sum(args)\n",
    "\n",
    "print(sum_.__doc__)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 93,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "6"
      ]
     },
     "execution_count": 93,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sum_(1,2,3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Function Annotations"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 98,
   "metadata": {},
   "outputs": [],
   "source": [
    "# But more here\n",
    "def f(ham: str, eggs: str = 'eggs') -> str: # comment not here\n",
    "    print(\"Annotations:\", f.__annotations__)\n",
    "    print(\"Arguments:\", ham, eggs)\n",
    "    return ham + ' and ' + eggs\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 96,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Annotations: {'ham': <class 'str'>, 'eggs': <class 'str'>, 'return': <class 'str'>}\n",
      "Arguments: spam eggs\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "'spam and eggs'"
      ]
     },
     "execution_count": 96,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "f('spam')\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Intermezzo: Coding Style"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- Use 4-space indentation, and no tabs.\n",
    "- Wrap lines so that they don’t exceed 79 characters.\n",
    "- Use blank lines to separate functions and classes, and larger blocks of code inside functions.\n",
    "- When possible, put comments on a line of their own.\n",
    "- Use docstrings.\n",
    "- Use spaces around operators and after commas\n",
    "- Name your classes and functions consistently\n",
    "    - UpperCamelCase for classes\n",
    "    - lowercase_with_underscores for functions and methods\n",
    "    - Always use self as the name for the first method argument\n",
    "- Don’t use fancy encodings if your code is meant to be used in international environments. Python’s default, UTF-8, or even plain ASCII work best in any case.\n",
    "- Likewise, don’t use non-ASCII characters in identifiers if there is only the slightest chance people speaking a different language will read or maintain the code."
   ]
  }
 ],
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