Jupyter

Jupyter notebook is formerly known as IPython notebook, it is a tool that helps you create readable analyses. Jupyter works with python kernel by default, but it also supports many other kernels.

Keyboard shortcurts

• Cmd + Shift + P: open command palette

Set environment variables

# The line below sets the environment
# variable OMP_NUM_THREADS
%env OMP_NUM_THREADS=4

env: OMP_NUM_THREADS=4

Execute python code

# this will execute and show the output from
# all code cells of the specified notebook
%run ./helloworld.py

Hello, TensorFlow!
[ 2.  4.  6.]
[[  2.   4.   6.]
 [  8.  10.  12.]]

load code to current cell

# %load helloworld.py
#!/usr/bin/env python
import tensorflow as tf
# Create a Constant op
# The op is added as a node to the default graph.
#
# The value returned by the constructor represents the output
# of the Constant op.
hello = tf.constant('Hello, TensorFlow!')
x = tf.placeholder("float", 3)
a = tf.placeholder("float", shape=[None, 3])
y = x*2
b = a*2
# Start tf session
sess = tf.Session()
sess.run(tf.initialize_all_tables())
print sess.run(hello)
print sess.run(y, feed_dict={x:[1,2,3]})
print sess.run(b, feed_dict={a:[[1,2,3], [4,5,6]]})
sess.close()

Pass variables between notebooks

data = 'this is the string I want to pass to different notebook'
%store data
del data # This has deleted the variable
%store -r data
print(data)

Stored 'data' (str)
this is the string I want to pass to different notebook

Plot inline

%matplotlib inline
from matplotlib import pyplot as plt
import numpy
x = numpy.linspace(0, 1, 1000)**1.5;
plt.hist(x);

Latex forumlas

$$ P(A \mid B) = \frac{P(B \mid A) \, P(A)}{P(B)} $$

Writing functions in other languages

!pip install cython fortran-magic
%load_ext Cython
%%cython
def myltiply_by_2(float x):
    return 2.0 * x
myltiply_by_2(23.)

Other jupyter magic

• %matplotlib inline: plot inline.
• %who: List all variables of global scope.
• %%time and %timeit: timing the code.
• %lsmagic: list magic commands
• %%writefile pythoncode.py: export contents of the cell to pythoncode.py
• %pycat pythoncode.py: show the contents of an external script
• %prun: Show how much time your program spent in each function.
• %pdb: debugging with pdb.
• !pip install numpy: executing shell commands.
• %%bash, %%HTML, %%ruby, %%R: swith to other kernel.

Jupyter-contrib extensions

!pip install https://github.com/ipython-contrib/jupyter_contrib_nbextensions/tarball/master
!pip install jupyter_nbextensions_configurator
!jupyter contrib nbextension install --user
!jupyter nbextensions_configurator enable --user

Create a presentation

!pip install RISE
jupyter-nbextension install rise --py --sys-prefix
jupyter-nbextension enable rise --py --sys-prefix

Jupyter themes

pip install --upgrade jupyterthemes
jt -T -N -t grade3