Assignment-5.ipynb

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    "# Dictionaries\n",
    "\n",
    "##  Its an unordered collection of data values, used to store data values like a map, which unlike other Data Types that hold only a single value as an element, Dictionary holds key:value pair. Key-value is provided in the dictionary to make it more optimized. "
   ]
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   "cell_type": "code",
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     "text": [
      "{}\n",
      "0\n",
      "<class 'dict'>\n"
     ]
    }
   ],
   "source": [
    "## Empty Dictionaries\n",
    "emptyDict = {}\n",
    "print(emptyDict)\n",
    "print(len(emptyDict))\n",
    "print(type(emptyDict))"
   ]
  },
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   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
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     "name": "stdout",
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     "text": [
      "42\n",
      "1\n"
     ]
    }
   ],
   "source": [
    "dict = {'foo' : 42}\n",
    "print(dict['foo'])\n",
    "print(len(dict))"
   ]
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Differences between list and Dictonary \n",
    " - To access values in list you have to give index, whereas in dictonaries you have to give keys.\n",
    " - List stores data sequentially, whereas Dictonary doesnot stores data sequentially thats why we access values with help of key.\n"
   ]
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   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "ename": "KeyError",
     "evalue": "'foo'",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mKeyError\u001b[0m                                  Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-18-23eff5f25f73>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[0;32m      1\u001b[0m \u001b[0mspam\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;33m{\u001b[0m\u001b[1;34m'bar'\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;36m100\u001b[0m\u001b[1;33m}\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      2\u001b[0m \u001b[1;31m## we will get key error as we haven't defined any key:value pair named foo\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 3\u001b[1;33m \u001b[0mspam\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;34m'foo'\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mKeyError\u001b[0m: 'foo'"
     ]
    }
   ],
   "source": [
    "spam = {'bar':100}\n",
    "## we will get key error as we haven't defined any key:value pair named foo\n",
    "spam['foo']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
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     "execution_count": 23,
     "metadata": {},
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   "source": [
    "spam = {'cat':'meow','dog':'bow'}\n",
    "'cat' in spam.keys()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
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     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
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   "source": [
    "'cat' in spam"
   ]
  },
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   "cell_type": "markdown",
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   "source": [
    "## There is no difference proved in above code as in operator checks whether a value exists as a key in the dictionary or not."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
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     "execution_count": 25,
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   "source": [
    "'cat' in spam"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
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     "execution_count": 26,
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   "source": [
    "'cat' in spam.values()"
   ]
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## In the above 2 blocks of code 'cat' in spam finds if there is a key named 'cat' whereas 'cat' in spam.values() finds 'cat' in values of dictonary"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'cat': 'meow', 'dog': 'bow', 'color': 'black'}"
      ]
     },
     "execution_count": 36,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "## shortcut for the following code?\n",
    "## if 'color' not in spam:\n",
    "##    spam['color'] = 'black'\n",
    "spam.setdefault('color', 'black')\n",
    "spam['color']\n",
    "spam"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 70,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{                                                 'cat': 'meow',\n",
      "                                                  'color': 'black',\n",
      "                                                  'dog': 'bow'}\n"
     ]
    }
   ],
   "source": [
    "import pprint\n",
    "pprint.pprint(spam,indent = 50,width=10, compact=False)"
   ]
  }
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