In [7]:

    

# for ipython notebooks this display images inline and imports 
# numpy and matplotlib
%pylab inline

# ----- Future Libraries for Python 3 portability
from __future__ import print_function
from future.builtins import range

# ---- Standard Libraries (not imported by pylab)
import time

# ---- Scientific Libraries (not imported by pylab)
import pandas as pd
import scipy as sp


    

    




Populating the interactive namespace from numpy and matplotlib






    




WARNING: pylab import has clobbered these variables: ['product']
`%matplotlib` prevents importing * from pylab and numpy

In [2]:

    

# Problem 1
x = [0, 1, [2]]
x[2][0] = 3
print(x)
# this should print [0, 1, [3]]
x[2].append(4)
print(x)
# this should print [0, 1, [3, 4]]
x[2] = 2
print(x)
# this should print [0, 1, 2]


    

    




[0, 1, [3]]
[0, 1, [3, 4]]
[0, 1, 2]

In [3]:

    

# Problem 2
def my_sum(a_list):
    the_sum = 0
    for n in a_list:
        the_sum += n
    
    return the_sum

print(my_sum([1, 2, 3, 4]))

# Problem 3
def str_sum(a_list, separator=" "):
    return separator.join(a_list)

print(str_sum(["aa", "bb", "cc"], ""))


    

    




10
aabbcc

In [4]:

    

# Problem 4
def product(a_list):
    """ Using a python list and standard python. """
    the_prod = 1
    for n in a_list:
        the_prod *= n
    
    return the_prod

def np_prod(a_list):
    """ Convert python list to numpy and use np for multiplication. """
    return np.prod(a_list)

print(product([1, 2, 3]))
print(np_prod([1, 2, 3]))


    

    




6
6

In [13]:

    

# Problem 5
def factorial(x):
    """ Using standard python and no previous functions. """
    fact = 1
    for n in range(1, x + 1):
        fact *= n
        
    return fact

# def prod_fact(x):
#     """ Use the product function from above. """
#     return product(range(1, x + 1))

# as lambda function
prod_fact = lambda x: product(range(1, x + 1))

def np_factorial(x):
    """ Use numpy to compute the factorial. 
    
    per SO at 
    http://stackoverflow.com/questions/21753841/factorial-in-numpy-and-scipy
    numpy.math = scipy.math = math but scipy.misc uses a different function.
    """
    import scipy.misc
    return scipy.misc.factorial(x)

print(factorial(5))
print(prod_fact(5))
print(np_factorial(5))


    

    




120
120
120.0

In [39]:

    

import time
start_time = time.time()
from functools import reduce
sqrs = reduce(lambda x, y: x + y, 
              map(lambda x: x * x, (i for i in range(1, 10**7))))
round(time.time() - start_time, 3)


    

    
Out[39]:





3.967

In [50]:

    

import time
start_time = time.time()
sum((i**2 for i in range(1, 10**7)))
round(time.time() - start_time, 3)


    

    
Out[50]:





4.51

In [52]:

    

improvement = (1 - 3.967/4.51) * 100
print(round(improvement, 2))


    

    




12.04