lab05
March 6, 2020
[1]:
# Initialize OK
from
client.api.notebook
import
Notebook
ok
=
Notebook(
'lab05.ok'
)
=====================================================================
Assignment: Simulations
OK, version v1.12.5
=====================================================================
1
Lab 5: Simulations
Welcome to Lab 5!
We will go over
iteration
and
simulations
, as well as introduce the concept of
randomness
.
The data used in this lab will contain salary data and other statistics for basketball players from the
2014-2015 NBA season. This data was collected from the following sports analytic sites:
Basketball
Reference
and
Spotrac
.
First, set up the tests and imports by running the cell below.
[2]:
# Run this cell, but please don't change it.
# These lines import the Numpy and Datascience modules.
import
numpy
as
np
from
datascience
import
*
# These lines do some fancy plotting magic
import
matplotlib
%
matplotlib
inline
import
matplotlib.pyplot
as
plt
plt
.
style
.
use(
'fivethirtyeight'
)
# Don't change this cell; just run it.
from
client.api.notebook
import
Notebook
ok
=
Notebook(
'lab05.ok'
)
1

=====================================================================
Assignment: Simulations
OK, version v1.12.5
=====================================================================
1.1
1. Nachos and Conditionals
In Python, the boolean data type contains only two unique values:
True
and
False
. Expressions
containing comparison operators such as
<
(less than),
>
(greater than), and
==
(equal to) evaluate
to Boolean values. A list of common comparison operators can be found below!
Run the cell below to see an example of a comparison operator in action.
[3]:
3 > 1 + 1
[3]:
True
We can even assign the result of a comparison operation to a variable.
[4]:
result
= 10 / 2 == 5
result
[4]:
True
Arrays are compatible with comparison operators. The output is an array of boolean values.
[5]:
make_array(
1
,
5
,
7
,
8
,
3
,
-1
)
> 3
[5]:
array([False,
True,
True,
True, False, False])
One day, when you come home after a long week, you see a hot bowl of nachos waiting on the dining
table! Let’s say that whenever you take a nacho from the bowl, it will either have only
cheese
,
only
salsa
,
both
cheese and salsa, or
neither
cheese nor salsa (a sad tortilla chip indeed).
Let’s
try
and
simulate
taking
nachos
from
the
bowl
at
random
using
the
function,
np.random.choice(...)
.
1.1.1
np.random.choice
np.random.choice
picks one item at random from the given array. It is equally likely to pick any
of the items. Run the cell below several times, and observe how the results change.
[6]:
nachos
=
make_array(
'cheese'
,
'salsa'
,
'both'
,
'neither'
)
np
.
random
.
choice(nachos)
[6]:
'both'
2

To repeat this process multiple times, pass in an int
n
as the second argument to return
n
different
random choices. By default,
np.random.choice
samples
with replacement
and returns an
array
of items.
Run the next cell to see an example of sampling with replacement 10 times from the
nachos
array.
[7]:
np
.
random
.
choice(nachos,
10
)
[7]:
array(['both', 'neither', 'salsa', 'salsa', 'neither', 'neither', 'salsa',
'both', 'cheese', 'neither'], dtype='<U7')
To
count
the
number
of
times
a
certain
type
of
nacho
is
randomly
chosen,
we
can
use
np.count_nonzero
1.1.2
np.count_nonzero
np.count_nonzero
counts the number of non-zero values that appear in an array. When an array of
boolean values are passed through the function, it will count the number of
True
values (remember
that in Python,
True
is coded as 1 and
False
is coded as 0.)