Jupyter Tidbit: Display handles

README.md

Summary

IPython's display() function can return a DisplayHandle object. You can use a DisplayHandle to update the output of one cell from any other cell in a Jupyter Notebook.

Example

The display_handle.ipynb notebook below calls display(display_id=True) to get a display handle instance. It then uses the DisplayHandle.display method to show some initial, static Markdown. Later, in a different cell, it calls DisplayHandle.update in a loop to show a range of emoji characters.

Why is this useful?

You can use display handles to redraw matplotlib plots, re-render DataFrame tables, print log file updates, etc. from code executed anywhere in the notebook.

display_handle.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import itertools\n",
    "import time\n",
    "\n",
    "from IPython.display import Markdown"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Make a display handle."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "dh = display(display_id=True)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Show some Markdown (or plain text, or a plot, or ...)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "display(Markdown('# Display Update Fun'))\n",
    "dh.display(Markdown(''))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Update the display above. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for i in itertools.cycle(range(0x1F600, 0x1F650)):\n",
    "    dh.update(Markdown(f'## &#{i}; {hex(i)}'))\n",
    "    time.sleep(0.5)"
   ]
  }
 ],
 "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": "3.6.5"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}