02-Iterators and Generators Homework.ipynb

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    "___\n",
    "\n",
    "<a href='https://www.udemy.com/user/joseportilla/'><img src='../Pierian_Data_Logo.png'/></a>\n",
    "___\n",
    "<center><em>Content Copyright by Pierian Data</em></center>"
   ]
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   "source": [
    "# Iterators and Generators Homework \n",
    "\n",
    "### Problem 1\n",
    "\n",
    "Create a generator that generates the squares of numbers up to some number N."
   ]
  },
  {
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   "source": [
    "def gensquares(N):\n",
    "    \n",
    "    for squares in range(N):\n",
    "        yield squares ** 2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 79,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
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     "text": [
      "0\n",
      "1\n",
      "4\n",
      "9\n",
      "16\n",
      "25\n",
      "36\n",
      "49\n",
      "64\n",
      "81\n"
     ]
    }
   ],
   "source": [
    "for x in gensquares(10):\n",
    "    print(x)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 2\n",
    "\n",
    "Create a generator that yields \"n\" random numbers between a low and high number (that are inputs). <br>Note: Use the random library. For example:"
   ]
  },
  {
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       "7"
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   "source": [
    "import random\n",
    "\n",
    "random.randint(1,10)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "def rand_num(low,high,n):\n",
    "    \n",
    "    for rand in range(n):\n",
    "        yield random.randint(low, high)\n",
    "        "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
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    {
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     "text": [
      "2\n",
      "3\n",
      "7\n",
      "7\n",
      "1\n",
      "4\n",
      "10\n",
      "7\n",
      "2\n",
      "8\n",
      "6\n",
      "3\n"
     ]
    }
   ],
   "source": [
    "for num in rand_num(1,10,12):\n",
    "    print(num)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Another process\n",
    "\n",
    "from random import randint\n",
    "\n",
    "def rand_nums (low, high, n):\n",
    "    \n",
    "    for x in range(n):\n",
    "        yield randint(low, high)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
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     "text": [
      "5\n",
      "19\n",
      "18\n",
      "5\n"
     ]
    }
   ],
   "source": [
    "for numbers in rand_nums(1,20,4):\n",
    "    print (numbers)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 3\n",
    "\n",
    "Use the iter() function to convert the string below into an iterator:\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 84,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "h\n"
     ]
    }
   ],
   "source": [
    "s = 'hello'\n",
    "\n",
    "#code here\n",
    "\n",
    "chng_iter = iter(s)\n",
    "\n",
    "print (next(chng_iter))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 85,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "e\n"
     ]
    }
   ],
   "source": [
    "print (next(chng_iter))"
   ]
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   "cell_type": "code",
   "execution_count": 86,
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     "name": "stdout",
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     "text": [
      "l\n"
     ]
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   "source": [
    "print (next(chng_iter))"
   ]
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   "source": [
    "### Problem 4\n",
    "Explain a use case for a generator using a yield statement where you would not want to use a normal function with a return statement.<br><br><br><br><br><br>\n",
    "\n"
   ]
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   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Where there are huge data involved, storing the data is not feasible or possible, as it will block the memeory. \n",
    "# Rather Using yield statement eases things up."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  },
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   "cell_type": "markdown",
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   "source": [
    "### Extra Credit!\n",
    "Can you explain what *gencomp* is in the code below? (Note: We never covered this in lecture! You will have to do some Googling/Stack Overflowing!)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
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     "text": [
      "4\n",
      "5\n"
     ]
    }
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   "source": [
    "my_list = [1,2,3,4,5]\n",
    "\n",
    "gencomp = (item for item in my_list if item > 3)   # Only by changing to () from [] , it will be a generator\n",
    "\n",
    "for item in gencomp:\n",
    "    print(item)"
   ]
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  {
   "cell_type": "code",
   "execution_count": 69,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_list = [1,2,3,4,5]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 70,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "4\n",
      "5\n"
     ]
    }
   ],
   "source": [
    "# A Normal for loop\n",
    "\n",
    "for item in my_list:\n",
    "    if item > 3:\n",
    "        print (item)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# A generator expression is like a list comprehension, but instead of finding all the items you're interested and \n",
    "# packing them into list, it waits, and yields each item out of the expression, one by one."
   ]
  },
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   "cell_type": "markdown",
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   "source": [
    "Hint: Google *generator comprehension*!\n",
    "\n",
    "# Great Job!"
   ]
  }
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