A brief tour of the IPython notebook

This document will give you a brief tour of the capabilities of the IPython notebook.
You can view its contents by scrolling around, or execute each cell by typing Shift-Enter.

The rest of the notebooks in this directory illustrate various other aspects and capabilities of the IPython notebook; some of them may require additional libraries to be executed.

NOTE: This notebook must be run from its own directory, so you must cd to this directory and then start the notebook, but do not use the --notebook-dir option to run it from another location.

The first thing you need to know is that you are still controlling the same old IPython you're used to, so things like shell aliases and magic commands still work:

In [1]:
pwd
Out[1]:
u'/home/fperez/ipython/tutorial/notebooks'
In [2]:
ls
animation.m4v                        P10 Basic Interface.ipynb
argv.py                              P15 Parallel Magics.ipynb
cat.py*                              P20 Multiplexing.ipynb
Cell Magics.ipynb                    P21 LoadBalancing.ipynb
Display control.ipynb                P30 Working with MPI.ipynb
figs/                                P99 Summary.ipynb
foo.py                               PX01 Example - Remote Iteration.ipynb
lnum.py*                             python-logo.svg
myscript.py                          PZ Performance.ipynb
nb@                                  soln/
nbtour.ipynb                         text_analysis.py*
P01 Overview and Architecture.ipynb
In [3]:
message = 'The IPython notebook is great!'
# note: the echo command does not run on Windows, it's a unix command.
!echo $message
The IPython notebook is great!

Plots with matplotlib

IPython adds an 'inline' matplotlib backend, which embeds any matplotlib figures into the notebook.

In [4]:
%pylab inline
Welcome to pylab, a matplotlib-based Python environment [backend: module://IPython.zmq.pylab.backend_inline].
For more information, type 'help(pylab)'.
In [5]:
x = linspace(0, 3*pi, 500)
plot(x, sin(x**2))
title('A simple chirp');

You can paste blocks of input with prompt markers, such as those from the official Python tutorial

In [6]:
>>> the_world_is_flat = 1
>>> if the_world_is_flat:
...     print "Be careful not to fall off!"
Be careful not to fall off!

Errors are shown in informative ways:

In [7]:
%run non_existent_file
ERROR: File `u'non_existent_file.py'` not found.
In [8]:
x = 1
y = 4
z = y/(1-x)
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)
<ipython-input-8-dc39888fd1d2> in <module>()
      1 x = 1
      2 y = 4
----> 3 z = y/(1-x)

ZeroDivisionError: integer division or modulo by zero

When IPython needs to display additional information (such as providing details on an object via x? it will automatically invoke a pager at the bottom of the screen:

In [9]:
magic

Non-blocking output of kernel

If you execute the next cell, you will see the output arriving as it is generated, not all at the end.

In [10]:
import time, sys
for i in range(8):
    print i,
    time.sleep(0.5)
0 1 2 3 4 5 6 7

Clean crash and restart

We call the low-level system libc.time routine with the wrong argument via ctypes to segfault the Python interpreter:

In [ ]:
import sys
from ctypes import CDLL
# This will crash a Linux or Mac system; equivalent calls can be made on Windows
dll = 'dylib' if sys.platform == 'darwin' else 'so.6'
libc = CDLL("libc.%s" % dll) 
libc.time(-1)  # BOOM!!

Markdown cells can contain formatted text and code

You can italicize, boldface

  • build
  • lists

and embed code meant for illustration instead of execution in Python:

def f(x):
    """a docstring"""
    return x**2

or other languages:

if (i=0; i<n; i++) {
  printf("hello %d\n", i);
  x += 4;
}

Courtesy of MathJax, you can include mathematical expressions both inline: $e^{i\pi} + 1 = 0$ and displayed:

$$e^x=\sum_{i=0}^\infty \frac{1}{i!}x^i$$

Rich displays: include anyting a browser can show

Note that we have an actual protocol for this, see the display_protocol notebook for further details.

Images

In [1]:
from IPython.display import Image
Image(filename='figs/logo.png')
Out[1]:

An image can also be displayed from raw data or a url

In [2]:
Image(url='http://python.org/images/python-logo.gif')
Out[2]:

SVG images are also supported out of the box (since modern browsers do a good job of rendering them):

In [3]:
from IPython.display import SVG
SVG(filename='figs/python-logo.svg')
Out[3]:
image/svg+xml

Video

And more exotic objects can also be displayed, as long as their representation supports the IPython display protocol.

For example, videos hosted externally on YouTube are easy to load (and writing a similar wrapper for other hosted content is trivial):

In [1]:
from IPython.display import YouTubeVideo
# a talk about IPython at Sage Days at U. Washington, Seattle.
# Video credit: William Stein.
YouTubeVideo('1j_HxD4iLn8')
Out[1]:

Using the nascent video capabilities of modern browsers, you may also be able to display local videos. At the moment this doesn't work very well in all browsers, so it may or may not work for you; we will continue testing this and looking for ways to make it more robust.

The following cell loads a local file called animation.m4v, encodes the raw video as base64 for http transport, and uses the HTML5 video tag to load it. On Chrome 15 it works correctly, displaying a control bar at the bottom with a play/pause button and a location slider.

In [2]:
from IPython.display import HTML
video = open("figs/animation.m4v", "rb").read()
video_encoded = video.encode("base64")
video_tag = '<video controls alt="test" src="data:video/x-m4v;base64,{0}">'.format(video_encoded)
HTML(data=video_tag)
Out[2]:

Local Files

The above examples embed images and video from the notebook filesystem in the output areas of code cells. It is also possible to request these files directly in markdown cells if they reside in the notebook directory via relative urls prefixed with files/:

files/[subdirectory/]<filename>


For example, in the example notebook folder, we have the Python logo, addressed as:

<img src="figs/python-logo.svg" />

and a video with the HTML5 video tag:

<video controls src="figs/animation.m4v" />

External sites

You can even embed an entire page from another site in an iframe; for example this is today's Wikipedia page for mobile users:

In [3]:
HTML('<iframe src=http://en.mobile.wikipedia.org/?useformat=mobile width=700 height=350>')
Out[3]: