007_dictionaries.ipynb

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 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 006_dictionaries\n",
    "\n",
    "[Source](https://github.com/iArunava/Python-TheNoTheoryGuide/)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Simple Dictionary\n",
    "# Dictionary allows to have key:value pairs\n",
    "d1 = {\"Jennifer\":8, 'A':65, 66:'B', 9.45:\"Decimals\"}\n",
    "\n",
    "print (d1[\"Jennifer\"])\n",
    "print (d1['A'])\n",
    "print (d1[66])\n",
    "print (d1[9.45])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Adding new kay:value pairs\n",
    "d1 = {\"Jennifer\":8, 'A':65, 66:'B', 9.45:\"Decimals\"}\n",
    "\n",
    "d1[\"Scarlett\"] = 8\n",
    "d1[7.56]       = \"Is a decimal!\"\n",
    "d1['Q']        = 17\n",
    "\n",
    "print (d1[\"Scarlett\"])\n",
    "print (d1[7.56])\n",
    "print (d1['Q'])\n",
    "\n",
    "print (d1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Declaring an empty dictionary\n",
    "d1 = {}\n",
    "\n",
    "# Add new values\n",
    "d1[\"Jennifer\"] = \"Python\"\n",
    "d1[\"Scarlett\"] = \"Python\"\n",
    "d1[45]         = 56\n",
    "\n",
    "print (d1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Modifying values in a dictionary\n",
    "d1 = {\"Python\":\"Is a language\", \"Jennifer\":\"Feels like a supergirl with Python\"}\n",
    "\n",
    "d1[\"Python\"] = \"Is Love\"\n",
    "d1[\"Jennifer\"] = 8\n",
    "print (d1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Removing Key:Value pairs\n",
    "d1 = {\"Key\":\"Value\", \"Jennifer\":\"Scarlett\", \"Scarlett\":\"Jennifer\"}\n",
    "\n",
    "del d1[\"Key\"]\n",
    "print (d1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Storing a dictionary inside a dictionary\n",
    "d1 = {'A':65, 'B':66, 'C':67, 'D': {\n",
    "    \"Breaking\": \"Dict into dicts\", \n",
    "    \"Inception\": \"All over\", \n",
    "    '!': \"XD\"}, \n",
    "    'E':69, \n",
    "    \"What happened with D?\": \"It became a 'D'ictionary! XD\",\n",
    "    66:66}\n",
    "\n",
    "print (d1['D'][\"Inception\"])\n",
    "print (d1[\"What happened with D?\"])\n",
    "print ('\\n')\n",
    "print (d1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Looping through a dictionary\n",
    "for key, value in d1.items():\n",
    "    print(\"Key: \"    + str(key))\n",
    "    print (\"Value: \" + str(value))\n",
    "    print('\\n')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Looping through the keys in dictionary\n",
    "for key in d1.keys():\n",
    "    print(\"Key: \"    + str(key))\n",
    "    print (\"Value: \" + str(d1[key]))\n",
    "    print('\\n')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Note: Default behaviour is to loop through keys if not specified d1.keys()\n",
    "for k in d1:\n",
    "    print(\"Key: \"    + str(k))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Check if a particular key is  present\n",
    "if 'F' not in d1.keys():\n",
    "    print (\"What happened to F?\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Looping through dictonary keys in sorted order (increasing)\n",
    "for key in sorted(d1.keys()):\n",
    "    print (\"Key :\" + key + '\\t' + \"Value :\" + str(d1[key]) + '\\n')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Looping through dictonary keys in sorted order (decreasing)\n",
    "for key in sorted(d1.keys(), reverse=True):\n",
    "    print (\"Key :\" + key + '\\t' + \"Value :\" + str(d1[key]) + '\\n')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Looping through values in dictionary (with repeats)\n",
    "# Note: If two or more keys have the same value then this method will print all of them\n",
    "for value in d1.values():\n",
    "    print (str(value).title())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# List in Dictionary\n",
    "d1 = {\"l1\":['A', 'B', 'C', 'D'],\n",
    "      \"l2\":['E', 'F', 'G', 'H'],\n",
    "       45 : \"qwerty\",\n",
    "      '$' : \"$Dollar$\"}\n",
    "\n",
    "# Accessing the elements in list\n",
    "print (d1[\"l1\"][2])\n",
    "print (d1[\"l2\"][-1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Looping over just the lists in dictionary\n",
    "for k in d1.keys():\n",
    "    if type(d1[k]) == list:\n",
    "        print (\"List :\" + k)\n",
    "        for val in d1[k]:\n",
    "            print (val)\n",
    "        print ('\\n')"
   ]
  }
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