#!/usr/bin/env python
# coding: utf-8

# # Customizing IPython - Extensions

# Extensions are just Python modules with a special function:
# 
# ```python
# def load_ipython_extension(ip):
#     do_anything()
# ```
# 
# `%load_ext module` imports the module, and calls `module.load_ipython_extension(ip)`
# with the IPython instance.
# 
# This allows modules or standalone extensions to manipulate IPython.
# Most often, extensions define new magics or work with the interactive namespace.
# 
# Cython is an example of a package that can be used as an IPython extension.
# This defines a few magics for executing Cython code interactively.

# In[1]:


get_ipython().run_cell_magic('cython', '', '\ncpdef noop():\n    pass\n')


# In[2]:


get_ipython().run_line_magic('load_ext', 'Cython')


# In[3]:


get_ipython().run_cell_magic('cython', '', 'cimport numpy\n\ncpdef cysum(numpy.ndarray[double] A):\n    """Compute the sum of an array"""\n    cdef double a=0\n    for i in range(A.shape[0]):\n        a += A[i]\n    return a\n')


# In[4]:


def pysum(A):
    """Compute the sum of an array"""
    a = 0
    for i in range(A.shape[0]):
        a += A[i]
    return a


# In[5]:


import numpy as np


# In[6]:


for sz in (100, 1000, 10000):
    A = np.random.random(sz)
    print("Python %i" % sz, end=' ')
    get_ipython().run_line_magic('timeit', 'pysum(A)')
    print("np.sum %i" % sz, end=' ')
    get_ipython().run_line_magic('timeit', 'A.sum()')
    print("Cython %i" % sz, end=' ')
    get_ipython().run_line_magic('timeit', 'cysum(A)')


# Let's see what Cython's `load_ipython_extension` function looks like

# In[7]:


import Cython


# In[8]:


get_ipython().run_line_magic('pinfo2', 'Cython.load_ipython_extension')


# In[9]:


from Cython.Build.IpythonMagic import CythonMagics
get_ipython().run_line_magic('pinfo2', 'CythonMagics')


# ## Our own extension

# Loading an extension can do as much or as little as you want.
# 
# Since we have been defining our timer magics, let's create an extension to make them available in any IPython session.

# In[10]:


get_ipython().run_line_magic('pycat', 'soln/mymagics.py')


# `%install_ext` is a function that can take any file path or URL, and puts the target into IPYTHONDIR/extensions

# In[11]:


get_ipython().run_line_magic('install_ext', 'soln/mymagics.py')


# In[12]:


get_ipython().run_line_magic('load_ext', 'mymagics')


# In[13]:


import time
get_ipython().run_line_magic('tic', '')
time.sleep(0.1)
get_ipython().run_line_magic('toc', '')


# In[14]:


get_ipython().run_line_magic('nbrun', '_Sample')


# For some example extensions, see [this repository](http://github.com/minrk/ipython_extensions).
# 
# Now we can get our magics with a single `%load_ext` call.
# Let's move on to [Configuring IPython](Customizing%20IPython%20-%20Config.ipynb),
# so we can see how to load our extension at startup.