|
| 1 | +{ |
| 2 | + "cells": [ |
| 3 | + { |
| 4 | + "cell_type": "markdown", |
| 5 | + "metadata": {}, |
| 6 | + "source": [ |
| 7 | + "# What is Jupyter and how do you use it?\n", |
| 8 | + "\n", |
| 9 | + "[Project Jupyter](http://jupyter.org) exists to develop software and standards for interactive computing. Jupyter, which you are using now, provides an interactive notebook which runs on a cloud-server, and with which you interact using a web browser.\n", |
| 10 | + "\n", |
| 11 | + "As installed, Jupyter provides two things:\n", |
| 12 | + "\n", |
| 13 | + "* An interactive Python notebook, which you are using now (this is an interactive notebook!)\n", |
| 14 | + "* An interactive bash terminal (we will use this later)\n", |
| 15 | + "\n", |
| 16 | + "What is an interactive Python notebook? It is a notebook that mixes documentation (like this!) with Python code (like below), with the output of that code.\n", |
| 17 | + "\n", |
| 18 | + "For example, below is the Python code to print \"Hello World\". Click on the below code and then press \"SHIFT+Return\". You should see that the code is run, and below \"Hello World\" will be printed." |
| 19 | + ] |
| 20 | + }, |
| 21 | + { |
| 22 | + "cell_type": "code", |
| 23 | + "execution_count": 3, |
| 24 | + "metadata": {}, |
| 25 | + "outputs": [ |
| 26 | + { |
| 27 | + "name": "stdout", |
| 28 | + "output_type": "stream", |
| 29 | + "text": [ |
| 30 | + "Hello World\n" |
| 31 | + ] |
| 32 | + } |
| 33 | + ], |
| 34 | + "source": [ |
| 35 | + "print(\"Hello World\")" |
| 36 | + ] |
| 37 | + }, |
| 38 | + { |
| 39 | + "cell_type": "markdown", |
| 40 | + "metadata": {}, |
| 41 | + "source": [ |
| 42 | + "The above code is interactive because it runs when you pressed \"SHIFT+Return\". It is also interactive because you can change it. For example, click again on the code and change \"Hello World\" to \"Hello Jupyter\". Press \"SHIFT+Return\" again and you should see \"Hello Jupyter\" printed.\n", |
| 43 | + "\n", |
| 44 | + "A code cell can have as much or little Python in it as you want. The below cell defines a function and then runs it in a loop. What do you think will be printed out when you select it and press \"SHIFT+Return\"? Have a go. Are you right?" |
| 45 | + ] |
| 46 | + }, |
| 47 | + { |
| 48 | + "cell_type": "code", |
| 49 | + "execution_count": 5, |
| 50 | + "metadata": {}, |
| 51 | + "outputs": [ |
| 52 | + { |
| 53 | + "name": "stdout", |
| 54 | + "output_type": "stream", |
| 55 | + "text": [ |
| 56 | + "10...\n", |
| 57 | + "9...\n", |
| 58 | + "8...\n", |
| 59 | + "7...\n", |
| 60 | + "6...\n", |
| 61 | + "5...\n", |
| 62 | + "4...\n", |
| 63 | + "3...\n", |
| 64 | + "2...\n", |
| 65 | + "1...\n", |
| 66 | + "Lift off!\n" |
| 67 | + ] |
| 68 | + } |
| 69 | + ], |
| 70 | + "source": [ |
| 71 | + "def countDown(start):\n", |
| 72 | + " for i in range(start, 0, -1):\n", |
| 73 | + " print(\"%d...\" % i)\n", |
| 74 | + " print(\"Lift off!\")\n", |
| 75 | + " \n", |
| 76 | + "countDown(10)" |
| 77 | + ] |
| 78 | + }, |
| 79 | + { |
| 80 | + "cell_type": "markdown", |
| 81 | + "metadata": {}, |
| 82 | + "source": [ |
| 83 | + "Each cell can use the variables and functions defined in previous cells. For example, the next cell sets the value of the variable `x` to 5, while the following cell then uses that to call the `countDown` function." |
| 84 | + ] |
| 85 | + }, |
| 86 | + { |
| 87 | + "cell_type": "code", |
| 88 | + "execution_count": 10, |
| 89 | + "metadata": {}, |
| 90 | + "outputs": [], |
| 91 | + "source": [ |
| 92 | + "x = 21" |
| 93 | + ] |
| 94 | + }, |
| 95 | + { |
| 96 | + "cell_type": "code", |
| 97 | + "execution_count": 9, |
| 98 | + "metadata": {}, |
| 99 | + "outputs": [ |
| 100 | + { |
| 101 | + "name": "stdout", |
| 102 | + "output_type": "stream", |
| 103 | + "text": [ |
| 104 | + "7...\n", |
| 105 | + "6...\n", |
| 106 | + "5...\n", |
| 107 | + "4...\n", |
| 108 | + "3...\n", |
| 109 | + "2...\n", |
| 110 | + "1...\n", |
| 111 | + "Lift off!\n" |
| 112 | + ] |
| 113 | + } |
| 114 | + ], |
| 115 | + "source": [ |
| 116 | + "countDown(x)" |
| 117 | + ] |
| 118 | + }, |
| 119 | + { |
| 120 | + "cell_type": "markdown", |
| 121 | + "metadata": {}, |
| 122 | + "source": [ |
| 123 | + "You can go back up and edit the value of `x`. For example, set `x` to 7 and press SHIFT+Return. This has changed `x`. However, it doesn't re-run any code that depends on `x`. That is for you to do. You need to click on the next cell `countDown(x)` and press SHIFT+Return again. You should then see that the code is run and updated.\n", |
| 124 | + "\n", |
| 125 | + "Because you can change any cell at any time, a notebook can get into a confused state. If we change `x` again to `21`, then the cell `countDown(x)`, is now out of date, as it depends on the old value of `x`. So, how can we know what state each cell is in?\n", |
| 126 | + "\n" |
| 127 | + ] |
| 128 | + }, |
| 129 | + { |
| 130 | + "cell_type": "code", |
| 131 | + "execution_count": null, |
| 132 | + "metadata": {}, |
| 133 | + "outputs": [], |
| 134 | + "source": [] |
| 135 | + } |
| 136 | + ], |
| 137 | + "metadata": { |
| 138 | + "kernelspec": { |
| 139 | + "display_name": "Python 3", |
| 140 | + "language": "python", |
| 141 | + "name": "python3" |
| 142 | + }, |
| 143 | + "language_info": { |
| 144 | + "codemirror_mode": { |
| 145 | + "name": "ipython", |
| 146 | + "version": 3 |
| 147 | + }, |
| 148 | + "file_extension": ".py", |
| 149 | + "mimetype": "text/x-python", |
| 150 | + "name": "python", |
| 151 | + "nbconvert_exporter": "python", |
| 152 | + "pygments_lexer": "ipython3", |
| 153 | + "version": "3.5.2" |
| 154 | + } |
| 155 | + }, |
| 156 | + "nbformat": 4, |
| 157 | + "nbformat_minor": 2 |
| 158 | +} |
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