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Author: jatinkatyal13

Lecture 4/.ipynb_checkpoints/1.Iterators_&_Generators-checkpoint.ipynb

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+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# <center>Intermediate Python (Part-1)</center>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# ***<center>Iterators and Generators</center>***\n",
+    "\n",
+    "<img src=https://i.imgur.com/e1Deq4a.jpg height=300 width=300>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 1. Iteration protocol in Python\n",
+    "\n",
+    "\n",
+    "- **Iteration:** repitition of a process.\n",
+    "- **Iterable:** a Python object which supports iteration.\n",
+    "- **Iterator:** a Python object to perform iteration over an iterable."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "![](http://nvie.com/img/iterable-vs-iterator.png)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Iteration Protocol in Python\n",
+    "\n",
+    "The **iteration protocol** is a fancy term meaning “how iterables actually work in Python”.\n",
+    "\n",
+    "1. For a class object to be an Iterable:\n",
+    "    - Can be passed to the iter function to get an iterator for them.\n",
+    "\n",
+    "2. For any Iterator:\n",
+    "    - Can be passed to the next function which gives their next item or raises StopIteration\n",
+    "    - Return themselves when passed to the iter function."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "![](https://image.slidesharecdn.com/pythonadvanced-151127114045-lva1-app6891/95/python-advanced-building-on-the-foundation-102-638.jpg?cb=1448910770)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "class Iterable:\n",
+    "    def __init__ (self):\n",
+    "        "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 2. Generators\n",
+    "\n",
+    "Simple **functions** or **expressions** used to create iterator.\n",
+    "\n",
+    "Let's write a function which return the factorial of first 10 natural numbers."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 22,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def factorial(n):\n",
+    "    fact = []\n",
+    "    k = 1\n",
+    "    for i in range(1,n+1):\n",
+    "        k *= i\n",
+    "        fact.append(k)\n",
+    "    return fact"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Let's make it memory efficient using generators!"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "![](https://paulohrpinheiro.xyz/texts/python/images/lazy-evaluation.jpg)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "![](http://nvie.com/img/relationships.png)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Generator expression\n",
+    "\n",
+    "Now, let us find the sum of squares of first 10 natural numbers, but this time, without any function!"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "This can also be converted into a generator **expression**!"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Let's sum up it all!\n",
+    "![](https://raw.github.com/wardi/iterables-iterators-generators/master/iterable_iterator_generator.png)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.6.3"
+  }
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+ "nbformat": 4,
+ "nbformat_minor": 2
+}