01-NavigatingTheNotebook.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Navigating the notebook"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Filename\n",
    "* click on the file name above to change it"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Menu bar\n",
    "* contains actions for the notebook, its cells, and the kernel"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Tool bar\n",
    "* buttons for common actions\n",
    "* hover over a button for info"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Execution Modes\n",
    "* **Edit mode**:  changing the content within a cell\n",
    "  \n",
    "  \n",
    "* **Command mode**:  performing actions on the notebook as a whole\n",
    "\n",
    "\n",
    "|  _ | Edit | Command |\n",
    "| --- | --- | --- |\n",
    "| cell outline | green | blue |\n",
    "| typing | inserts text | executes actions |\n",
    "| cursor |   inside cell | none |\n",
    "| indicator at top right | pencil | none |\n",
    "| how to get into it: | `Enter` | `Esc` |\n",
    "| _ | (or mouse click/double-click) |"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Make this cell go back and forth between edit and command mode"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Types of cells\n",
    "\n",
    "* **Code** and **Markdown**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# This is a code cell"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This is a markdown cell"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### We will come back to markdown, but first:  Running Code\n",
    "\n",
    "First and foremost, the Jupyter Notebook is an interactive environment for writing and running code. The notebook is capable of running code in a wide range of languages. \n",
    "\n",
    "Each notebook is associated with a single kernel.  This notebook is associated with the IPython kernel and therefore runs Python code."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Code cells allow you to enter and run code\n",
    "\n",
    "Run a code cell using `Shift-Enter` or pressing the <button class='btn btn-default btn-xs'><i class=\"icon-step-forward fa fa-step-forward\"></i></button> button in the toolbar above:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "a = 10"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(a)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "There are two other keyboard shortcuts for running code:\n",
    "\n",
    "* `Alt-Enter` runs the current cell and inserts a new one below.\n",
    "* `Ctrl-Enter` run the current cell and enters command mode."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Markdown cells allow you to enter marked-up text for descriptions, equations, etc."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "(double-click on this cell to see the markdown text)\n",
    "\n",
    "*Italic* and **bold** text\n",
    "\n",
    "* Bullet lists\n",
    "* or numbered lists\n",
    "  1. like 1\n",
    "  1. or 2\n",
    "  1. or 3\n",
    "\n",
    "Inline equations like $e^{i\\pi} = -1$ or displayed equations like $$e^x = \\sum_{i=0}^{\\infty} \\frac{x^i}{i!}$$\n",
    "\n",
    "Or links, like to a [markdown cheatsheet](https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Managing the Kernel\n",
    "\n",
    "Code is run in a separate process called the Kernel.  The Kernel can be interrupted or restarted.  Try running the following cell and then hit the <button class='btn btn-default btn-xs'><i class='icon-stop fa fa-stop'></i></button> button in the toolbar above."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import time\n",
    "time.sleep(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "If the Kernel dies you will be prompted to restart it. Here we call the low-level system libc.time routine with the wrong argument via\n",
    "ctypes to segfault the Python interpreter:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import sys\n",
    "from ctypes import CDLL\n",
    "# This will crash a Linux or Mac system\n",
    "# equivalent calls can be made on Windows\n",
    "\n",
    "# Uncomment these lines if you would like to see the segfault\n",
    "\n",
    "# dll = 'dylib' if sys.platform == 'darwin' else 'so.6'\n",
    "# libc = CDLL(\"libc.%s\" % dll) \n",
    "# libc.time(-1)  # BOOM!!"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Restarting the kernels\n",
    "\n",
    "The kernel maintains the state of a notebook's computations. You can reset this state by restarting the kernel. This is done by clicking on the <button class='btn btn-default btn-xs'><i class='fa fa-repeat icon-repeat'></i></button> in the toolbar above."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Cell menu\n",
    "\n",
    "The \"Cell\" menu has a number of menu items for running code in different ways. These include:\n",
    "\n",
    "* Run and Select Below\n",
    "* Run and Insert Below\n",
    "* Run All\n",
    "* Run All Above\n",
    "* Run All Below"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Output is asynchronous\n",
    "\n",
    "All output is displayed asynchronously as it is generated in the Kernel. If you execute the next cell, you will see the output one piece at a time, not all at the end."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import time, sys\n",
    "for i in range(8):\n",
    "    print(i)\n",
    "    time.sleep(1.0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Large outputs\n",
    "\n",
    "To better handle large outputs, the output area can be collapsed. Run the following cell and then single- or double- click on the active area to the left of the output:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for i in range(20):\n",
    "    print(i)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Beyond a certain point, output will scroll automatically:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for i in range(500):\n",
    "    print(2**i - 1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Useful commands\n",
    "\n",
    "* You can save yourself some time by remembering some common commands:\n",
    "    * **Basic**\n",
    "        * `Enter` -- go into Edit mode\n",
    "        * `Shift-Enter` -- execute the active cell\n",
    "        * `up-arrow / k` and `down-arrow / j` move the active cell selection\n",
    "    * **Saving**\n",
    "        * `s` -- saves the notebook\n",
    "    * **Cell Types**\n",
    "        * `y` for code, `m` for markdown\n",
    "    * **Cell Creation**\n",
    "        * `a` for creating cell above the active one, `b` for below\n",
    "    * **Cell Editing**\n",
    "        * `x` - cut, `c` - copy, `v` - paste, `d,d` -- \"d\" pressed twice will delete a cell\n",
    "        * `z` - undo deletion\n",
    "    * **HELP!!**\n",
    "        * `h`\n",
    "        * or go to Help Menu -> Keyboard Shortcuts"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Reference:  \n",
    "* Help Menu -> User Interface Tour\n",
    "* \"Running Code.ipynb\" taken from https://github.com/jupyter/notebook\n",
    "(notebook/docs/source/examples/Notebook/Running Code.ipynb)\n",
    "* See also https://jupyter-notebook.readthedocs.io/en/stable/examples/Notebook/examples_index.html"
   ]
  }
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