Code Cells¶

Code, Output, Streams¶

An empty code cell:

In [1]:

Two empty lines:

In [1]:

Leading/trailing empty lines:

In [1]:



# 2 empty lines before, 1 after

A simple output:

In [2]:

6 * 7

Out[2]:

The standard output stream:

In [3]:

print('Hello, world!')

Hello, world!

Normal output + standard output

In [4]:

print('Hello, world!')
6 * 7

Hello, world!

Out[4]:

The standard error stream is highlighted and displayed just below the code cell. The standard output stream comes afterwards (with no special highlighting). Finally, the “normal” output is displayed.

In [5]:

import sys

print("I'll appear on the standard error stream", file=sys.stderr, flush=True)
print("I'll appear on the standard output stream")
"I'm the 'normal' output"

I'll appear on the standard error stream

I'll appear on the standard output stream

Out[5]:

"I'm the 'normal' output"

Cell Magics¶

Cells can contain code in other languages by means of cell magics:

In [6]:

%%bash
for i in 1 2 3
do
    echo $i
done

1
2
3

Special Display Formats¶

See IPython example notebook.

TODO: tables? e.g. Pandas DataFrame?

In [7]:

from IPython.display import display

Local Image Files¶

In [8]:

from IPython.display import Image
i = Image(filename='images/notebook_icon.png')
i

Out[8]:

In [9]:

display(i)

For some reason this doesn’t work with Image(...):

In [10]:

from IPython.display import SVG
SVG(filename='images/python_logo.svg')

Out[10]:

Image URLs¶

In [11]:

Image(url='https://www.python.org/static/img/python-logo-large.png')

Out[11]:

In [12]:

Image(url='https://www.python.org/static/img/python-logo-large.png', embed=True)

Out[12]:

In [13]:

Image(url='http://jupyter.org/assets/nav_logo.svg')

Out[13]:

In [14]:

Image(url='https://www.python.org/static/favicon.ico')

Out[14]:

In [15]:

Image(url='http://python.org/images/python-logo.gif')

Out[15]:

Math¶

In [16]:

from IPython.display import Math
eq = Math(r"\int_{-\infty}^\infty f(x) \delta(x - x_0) dx = f(x_0)")
eq

Out[16]:

\[\int_{-\infty}^\infty f(x) \delta(x - x_0) dx = f(x_0)\]

In [17]:

display(eq)

\[\int_{-\infty}^\infty f(x) \delta(x - x_0) dx = f(x_0)\]

In [18]:

%%latex
\begin{equation}
\int_{-\infty}^\infty f(x) \delta(x - x_0) dx = f(x_0)
\end{equation}

\[\begin{equation} \int_{-\infty}^\infty f(x) \delta(x - x_0) dx = f(x_0) \end{equation}\]

YouTube Videos¶

In [19]:

from IPython.display import YouTubeVideo
YouTubeVideo('WAikxUGbomY')

Out[19]:

Arbitrary JavaScript Output (HTML only)¶

In [20]:

%%javascript

var text = document.createTextNode("Hello, I was generated with JavaScript!");
// Content appended to "element" will be visible in the output area:
element.appendChild(text);

Note:

jQuery should be available, but using the readthedocs.org default theme, it’s not. See the issue on Github. Other Sphinx themes are not affected by this.

Unsupported Output Types¶

If a code cell produces data with an unsupported MIME type, the Jupyter Notebook doesn’t generate any output. nbsphinx, however, shows a warning message.

In [21]:

display({
    'text/x-python': 'print("Hello, world!")',
    'text/x-haskell': 'main = putStrLn "Hello, world!"',
}, raw=True)

Data type cannot be displayed: text/x-python, text/x-haskell

ANSI Colors¶

The standard output and standard error streams may contain ANSI escape sequences to change the text and background colors.

In [22]:

print('BEWARE: \x1b[1;33;41mugly colors\x1b[m!', file=sys.stderr, flush=True)
print('ABC\x1b[43mDEF\x1b[35mGHI\x1b[1mJKL\x1b[49mMNO\x1b[39mPQR\x1b[22mSTU')

BEWARE: ugly colors!

ABCDEFGHIJKLMNOPQRSTU

The following code showing the 8 basic ANSI colors is based on http://tldp.org/HOWTO/Bash-Prompt-HOWTO/x329.html. Each of the 8 colors has an “intense” variation, which is used for bold text.

In [23]:

text = ' XYZ '
formatstring = '\x1b[{}m' + text + '\x1b[m'

print(' ' * 6 + ' ' * len(text) +
      ''.join('{:^{}}'.format(bg, len(text)) for bg in range(40, 48)))
for fg in range(30, 38):
    for bold in False, True:
        fg_code = ('1;' if bold else '') + str(fg)
        print(' {:>4} '.format(fg_code) + formatstring.format(fg_code) +
              ''.join(formatstring.format(fg_code + ';' + str(bg))
                      for bg in range(40, 48)))

            40   41   42   43   44   45   46   47
   30  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
 1;30  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
   31  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
 1;31  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
   32  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
 1;32  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
   33  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
 1;33  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
   34  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
 1;34  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
   35  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
 1;35  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
   36  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
 1;36  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
   37  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ 
 1;37  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ  XYZ

ANSI also supports a set of 256 indexed colors. The following code showing all of them is based on http://bitmote.com/index.php?post/2012/11/19/Using-ANSI-Color-Codes-to-Colorize-Your-Bash-Prompt-on-Linux.

In [24]:

formatstring = '\x1b[38;5;{0};48;5;{0}mX\x1b[1mX\x1b[m'

print('  + ' + ''.join('{:2}'.format(i) for i in range(36)))
print('  0 ' + ''.join(formatstring.format(i) for i in range(16)))
for i in range(7):
    i = i * 36 + 16
    print('{:3} '.format(i) + ''.join(formatstring.format(i + j)
                                      for j in range(36) if i + j < 256))

  +  0 1 2 3 4 5 6 7 8 91011121314151617181920212223242526272829303132333435
  0 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 16 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 52 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 88 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
124 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
160 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
196 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
232 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

You can even use 24-bit RGB colors:

In [25]:

start = 255, 0, 0
end = 0, 0, 255
length = 79
out = []

for i in range(length):
    rgb = [start[c] + int(i * (end[c] - start[c]) / length) for c in range(3)]
    out.append('\x1b['
               '38;2;{rgb[2]};{rgb[1]};{rgb[0]};'
               '48;2;{rgb[0]};{rgb[1]};{rgb[2]}mX\x1b[m'.format(rgb=rgb))
print(''.join(out))

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX