lab05.pdf - lab05 October 8, 2018 1 Lab 5: Simulations...

lab05
October 8, 2018
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.
In [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 plots
plots . style . use( ' fivethirtyeight ' )
# Don ' t change this cell; just run it.
from client.api.notebook import Notebook
ok = Notebook( ' lab05.ok ' )
_ = ok . auth(inline = True )
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Assignment: Simulations
OK, version v1.12.5
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1.1 1. Nachos and Conditionals
In Python, Boolean values can either be True or False . We get Boolean values when using com-
parison operators such as < (less than), > (greater than), and == (equal to). A list of common
comparison operators can be found below!
1

Run the cell below to see an example of a comparison operator in action.
Arrays are compatible with comparison operators. The output is an array of boolean values.
In [5]: make_array( 1 , 5 , 7 , 8 , 3 , -1 ) > 3
Out[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(arr) , where arr is the array that you’re using. Start by running the cell below
several times, and observe how the results change.
Question 1. Assume we took ten nachos at random, and stored the results in an array called
ten_nachos as done below. Find the number of nachos with only cheese using code (do not hard-
code the answer).
Hint: Our solution involves a comparison operator and the np.count_nonzero method.
2

Conditional Statements
A conditional statement is composed of a sequence of conditions that allow Python to choose
from different alternatives based on whether some condition is true.