08. Dictionary.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### A dictionary is a collection which is unordered, changeable and indexed. In Python dictionaries are written with curly brackets, and they have keys and values."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'brand': 'Ford', 'model': 'Mustang', 'year': 1964}\n"
     ]
    }
   ],
   "source": [
    "# creating a dictionary\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "print(thisdict)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Mustang'"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# accessing values\n",
    "\n",
    "x = thisdict[\"model\"]\n",
    "x"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Mustang'"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# using the get() function\n",
    "\n",
    "x = thisdict.get(\"model\")\n",
    "x"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'brand': 'Ford', 'model': 'Mustang', 'year': 2018}"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# updating the values\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "thisdict[\"year\"] = 2018\n",
    "\n",
    "thisdict"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "brand\n",
      "model\n",
      "year\n"
     ]
    }
   ],
   "source": [
    "# accessing the keys\n",
    "\n",
    "for x in thisdict:\n",
    "    print(x)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Ford\n",
      "Mustang\n",
      "2018\n"
     ]
    }
   ],
   "source": [
    "# accessing the values\n",
    "\n",
    "for x in thisdict:\n",
    "    print(thisdict[x])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Ford\n",
      "Mustang\n",
      "2018\n"
     ]
    }
   ],
   "source": [
    "# using the values() to access the values in a dict\n",
    "\n",
    "for x in thisdict.values():\n",
    "    print(x)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "brand Ford\n",
      "model Mustang\n",
      "year 2018\n"
     ]
    }
   ],
   "source": [
    "# accessing both the key and values\n",
    "\n",
    "for x, y in thisdict.items():\n",
    "    print(x, y)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Yes, 'model' is one of the keys in the thisdict dictionary\n"
     ]
    }
   ],
   "source": [
    "# checking if that particular string exists or not\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "if \"model\" in thisdict:\n",
    "    print(\"Yes, 'model' is one of the keys in the thisdict dictionary\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'brand': 'Ford', 'model': 'Mustang', 'year': 1964, 'color': 'red'}\n"
     ]
    }
   ],
   "source": [
    "# adding items to the list\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "thisdict[\"color\"] = \"red\"\n",
    "print(thisdict)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'brand': 'Ford', 'year': 1964}\n"
     ]
    }
   ],
   "source": [
    "# removing the items from the dict\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "thisdict.pop(\"model\")\n",
    "print(thisdict)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'brand': 'Ford', 'model': 'Mustang'}\n"
     ]
    }
   ],
   "source": [
    "# removing the last item from the dict\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "thisdict.popitem()\n",
    "print(thisdict)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'brand': 'Ford', 'year': 1964}\n"
     ]
    }
   ],
   "source": [
    "# using del keyword to remove the elements\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "del thisdict[\"model\"]\n",
    "print(thisdict)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "ename": "NameError",
     "evalue": "name 'thisdict' is not defined",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-18-a9d699000318>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[0;32m      7\u001b[0m }\n\u001b[0;32m      8\u001b[0m \u001b[1;32mdel\u001b[0m \u001b[0mthisdict\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 9\u001b[1;33m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mthisdict\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m: name 'thisdict' is not defined"
     ]
    }
   ],
   "source": [
    "# deleting the dictionary\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "del thisdict\n",
    "print(thisdict)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{}\n"
     ]
    }
   ],
   "source": [
    "# emptieing the dictionary\n",
    "\n",
    "thisdict = {\n",
    "  \"brand\": \"Ford\",\n",
    "  \"model\": \"Mustang\",\n",
    "  \"year\": 1964\n",
    "}\n",
    "thisdict.clear()\n",
    "print(thisdict)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'child1': {'name': 'Emil', 'year': 2004},\n",
       " 'child2': {'name': 'Tobias', 'year': 2007},\n",
       " 'child3': {'name': 'Linus', 'year': 2011}}"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# nested dictionary\n",
    "\n",
    "child1 = {\n",
    "  \"name\" : \"Emil\",\n",
    "  \"year\" : 2004\n",
    "}\n",
    "child2 = {\n",
    "  \"name\" : \"Tobias\",\n",
    "  \"year\" : 2007\n",
    "}\n",
    "child3 = {\n",
    "  \"name\" : \"Linus\",\n",
    "  \"year\" : 2011\n",
    "}\n",
    "\n",
    "myfamily = {\n",
    "  \"child1\" : child1,\n",
    "  \"child2\" : child2,\n",
    "  \"child3\" : child3\n",
    "}\n",
    "\n",
    "myfamily"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'child1': {'name': 'Emil', 'year': 2004},\n",
       " 'child2': {'name': 'Tobias', 'year': 2007},\n",
       " 'child3': {'name': 'Linus', 'year': 2011}}"
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# one dictionary containing multiple dictionaries\n",
    "\n",
    "myfamily = {\n",
    "  \"child1\" : {\n",
    "    \"name\" : \"Emil\",\n",
    "    \"year\" : 2004\n",
    "  },\n",
    "  \"child2\" : {\n",
    "    \"name\" : \"Tobias\",\n",
    "    \"year\" : 2007\n",
    "  },\n",
    "  \"child3\" : {\n",
    "    \"name\" : \"Linus\",\n",
    "    \"year\" : 2011\n",
    "  }\n",
    "}\n",
    "\n",
    "myfamily"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'brand': 'Ford', 'model': 'Mustang', 'year': 1964}\n"
     ]
    }
   ],
   "source": [
    "# creating a dictionary using the dict keyword\n",
    "\n",
    "thisdict = dict(brand=\"Ford\", model=\"Mustang\", year=1964)\n",
    "\n",
    "print(thisdict)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Dictionary Methods"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "\n",
    "* clear()\tRemoves all the elements from the dictionary\n",
    "* copy()\tReturns a copy of the dictionary\n",
    "* fromkeys()\tReturns a dictionary with the specified keys and values\n",
    "* get()\tReturns the value of the specified key\n",
    "* items()\tReturns a list containing the a tuple for each key value pair\n",
    "* keys()\tReturns a list containing the dictionary's keys\n",
    "* pop()\tRemoves the element with the specified key\n",
    "* popitem()\tRemoves the last inserted key-value pair\n",
    "* setdefault()\tReturns the value of the specified key. If the key does not exist: insert the key, with the specified value\n",
    "* update()\tUpdates the dictionary with the specified key-value pairs\n",
    "* values()\tReturns a list of all the values in the dictionary"
   ]
  }
 ],
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