Python/Unpacking Variables.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Packing & Unpacking Variables"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Assign variables\n",
    "In Python you can assign multiple variables at a time using commas."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n",
      "3\n"
     ]
    }
   ],
   "source": [
    "a, b, c = 1, 2, 3\n",
    "print(a)\n",
    "print(b)\n",
    "print(c)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Swap a pair of Variables in Python\n",
    "x,y = y,x"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "x=12, y=5\n"
     ]
    }
   ],
   "source": [
    "x = 5; y = 12\n",
    "x, y = y, x\n",
    "print('x=' + str(x) + ', y=' + str(y))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Swap a trio of Variables in Python\n",
    "Yes, this trick works for 3 variables too."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "88 99 77\n"
     ]
    }
   ],
   "source": [
    "x, y, z = 77, 88, 99\n",
    "z, x, y = x, y, z\n",
    "print(x, y, z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Split String into multiple variables\n",
    "But be careful because the number of variables must match the number of substrings from the split."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "4\n",
      "5\n",
      "6\n"
     ]
    }
   ],
   "source": [
    "a, b, c = '4 5 6'.split()\n",
    "print(a)\n",
    "print(b)\n",
    "print(c)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Splitting a List into variables is magically easy"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "8\n",
      "9\n",
      "10\n"
     ]
    }
   ],
   "source": [
    "my_list = [8, 9, 10]\n",
    "a, b, c = my_list\n",
    "print(a)\n",
    "print(b)\n",
    "print(c)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Split Tuple into variables"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "25 26 27\n"
     ]
    }
   ],
   "source": [
    "tup = (25,26,27)\n",
    "x, y, z = tup\n",
    "print(x, y, z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### This gives you a Tuple, not a List"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(8, 9, 10)\n",
      "<class 'tuple'>\n"
     ]
    }
   ],
   "source": [
    "var = a, b, c\n",
    "print(var)\n",
    "print(type(var))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### *args for Functions\n",
    "Used for passing a non-keyworded, variable-length argument list to a function.  \n",
    "Received as a Tuple."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "('Forest', 'Hill', 'High')\n",
      "<class 'tuple'>\n"
     ]
    }
   ],
   "source": [
    "def pack_it(*args):\n",
    "    print(args)\n",
    "    print(type(args))\n",
    "    \n",
    "x = 'Forest'; y = 'Hill'; z = 'High'\n",
    "pack_it(x, y, z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This unpacks the List before sending it, so it can be received by the function as separate variables."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Cullen\n",
      "McDonough\n"
     ]
    }
   ],
   "source": [
    "def unpack_it(x, y):\n",
    "    print(x)\n",
    "    print(y)\n",
    "    \n",
    "args = ['Cullen', 'McDonough']\n",
    "unpack_it(*args)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### **kwargs for Functions\n",
    "Used for passing keyworded, variable-length argument dictionary to functions.  \n",
    "This works, but it's kinda annoying because some normal Python dictionaries fail.  \n",
    "func (1:'Edsel', 2:'Betamax') does not work."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'a': 'Edsel', 'b': 'Betamax', 'c': 'mGaetz'}\n",
      "Edsel\n",
      "<class 'dict'>\n"
     ]
    }
   ],
   "source": [
    "def func(**losers):\n",
    "    print(losers)\n",
    "    print(losers['a'])\n",
    "    print(type(losers))\n",
    "    \n",
    "func(a='Edsel', b='Betamax', c='mGaetz')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This works, but it's kinda annoying because you have to use strings for the keys, so some normal Python dictionaries will give you an error. {1:'Edsel', 2:'Betamax'} fails."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Edsel\n"
     ]
    }
   ],
   "source": [
    "def func(a, b, c):\n",
    "    print(a)\n",
    "\n",
    "losers = {'a':'Edsel', 'b':'Betamax', 'c':'mGaetz'}\n",
    "func(**losers)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.7.0"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}