{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Alternative to if-else"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:47:15.487181Z",
     "start_time": "2020-07-31T16:47:15.480570Z"
    }
   },
   "outputs": [],
   "source": [
    "price_list = {\n",
    "'fish': 8,\n",
    "'beef': 7,\n",
    "'broccoli': 3,\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:47:27.087800Z",
     "start_time": "2020-07-31T16:47:27.084668Z"
    }
   },
   "outputs": [],
   "source": [
    "# query the dictionary twice -> not efficient\n",
    "def find_price(item):\n",
    "    if item in price_list:\n",
    "        return 'The price for {} is {}'.format(item, price_list[item])\n",
    "    else:\n",
    "        return 'The price for {} is not available'.format(item)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:48:37.957154Z",
     "start_time": "2020-07-31T16:48:37.954888Z"
    }
   },
   "outputs": [],
   "source": [
    "# .get() looks up a key and returns default value with the non-existent key\n",
    "def find_price(item):\n",
    "    return 'The price for {} is {}'.format(item, price_list.get(\n",
    "        item, 'not available'))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:48:47.750479Z",
     "start_time": "2020-07-31T16:48:47.740268Z"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'The price for fish is 8'"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "find_price('fish')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:48:54.154690Z",
     "start_time": "2020-07-31T16:48:54.151764Z"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'The price for cauliflower is not available'"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# returns default value with the non-existent key\n",
    "find_price('cauliflower')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Operations"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:50:38.045841Z",
     "start_time": "2020-07-31T16:50:38.036354Z"
    }
   },
   "outputs": [],
   "source": [
    "# okay\n",
    "def operations(operator, x, y):\n",
    "    if operator == 'add':\n",
    "        return x + y\n",
    "    elif operator == 'sub':\n",
    "        return x - y\n",
    "    elif operator == 'mul':\n",
    "        return x * y\n",
    "    elif operator == 'div':\n",
    "        return x / y"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:50:27.758351Z",
     "start_time": "2020-07-31T16:50:27.752404Z"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "16"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "operations('mul', 2, 8)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:50:52.856394Z",
     "start_time": "2020-07-31T16:50:52.847022Z"
    }
   },
   "outputs": [],
   "source": [
    "# better\n",
    "def operations(operator, x, y):\n",
    "    return {\n",
    "        'add': lambda: x+y,\n",
    "        'sub': lambda: x-y,\n",
    "        'mul': lambda: x*y,\n",
    "        'div': lambda: x/y,\n",
    "    }.get(operator, lambda: 'Not a valid operation')()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:50:56.854501Z",
     "start_time": "2020-07-31T16:50:56.851129Z"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "16"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "operations('mul', 2, 8)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "ExecuteTime": {
     "end_time": "2020-07-31T16:51:02.739125Z",
     "start_time": "2020-07-31T16:51:02.736367Z"
    }
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Not a valid operation'"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "operations('unknown', 2, 8)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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  "kernelspec": {
   "display_name": "Python 3",
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   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.8.3"
  },
  "latex_envs": {
   "LaTeX_envs_menu_present": true,
   "autoclose": false,
   "autocomplete": true,
   "bibliofile": "biblio.bib",
   "cite_by": "apalike",
   "current_citInitial": 1,
   "eqLabelWithNumbers": true,
   "eqNumInitial": 1,
   "hotkeys": {
    "equation": "Ctrl-E",
    "itemize": "Ctrl-I"
   },
   "labels_anchors": false,
   "latex_user_defs": false,
   "report_style_numbering": false,
   "user_envs_cfg": false
  },
  "toc": {
   "base_numbering": 1,
   "nav_menu": {},
   "number_sections": true,
   "sideBar": true,
   "skip_h1_title": false,
   "title_cell": "Table of Contents",
   "title_sidebar": "Contents",
   "toc_cell": false,
   "toc_position": {},
   "toc_section_display": true,
   "toc_window_display": false
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 "nbformat": 4,
 "nbformat_minor": 4
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