Basic Data Processing and Visualization Coursera Quiz Answers

Get All Weeks Basic Data Processing and Visualization Coursera Quiz Answers

This is the first course in the four-course specialization Python Data Products for Predictive Analytics, introducing the basics of reading and manipulating datasets in Python. In this course, you will learn what a data product is and go through several Python libraries to perform data retrieval, processing, and visualization.

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Basic Data Processing and Visualization Coursera Quiz Answers

Week 1 Quiz Answers

Quiz 1: Review: Data Products

Q1. W​hich of the following is not one of the steps in developing a data product strategy?

  • A​dopt for new situations
  • Share data
  • C​ommunicate goals
  • I​ntegrate analytics
  • B​uild teams
  • R​aise funding

Q2. W​hat is “derived data”?

  • Data after it has been cleaned and prepared for analysis
  • D​ata that isn’t interesting to analyze
  • D​ata that is mostly duplicated from other datasets
  • D​ata found by analyzing the raw data

Q3. Fill in the blank. Data products are systems that help us to understand data in order to gain insights and make .

  • models — analyses
  • models — predictions
  • predictions — models

Quiz 2: Review: Python and Jupyter

Q1. W​hat is the output of the code below?

x = 4
y = x
x += 1
print(y)
  • 4
  • 3​
  • 1​
  • 5​

Q2. Instead of curly brackets like in C++ or Java, what does Python use to differentiate inner lines of code?

  • I​ndentation
  • S​quare brackets
  • P​arentheses
  • E​xtra newlines

Q3. W​hat are some advantages of using Jupyter notebooks?

  • I​t supports multiple languages like Python, R, and Julia
  • I​t allows us to document data science with notes, code, and graphics
  • I​t allows others to reproduce and understand the steps behind the results of data science
  • I​t can be easily shared with colleagues and others
  • I​t can be used for easy real-time collaboration in data science

Q4. W​hat is wrong with the given code below?

print("hello world");
  • I​n Python, all methods need an explicitly defined calling object
  • I​n Python, lines are terminated with newlines instead of semicolons
  • I​n Python, a main function must be defined for code to run
  • I​n Python, strings do not need to be surrounded by double quotes

Week 2 Quiz Answers

Quiz 1: CSV and JSON Files

Q1. W​hy is the gzip library useful?

  • I​t gzips the opened file for us after we are done processing the data
  • I​t unzips gzipped files for us automatically and saves it on the computer
  • W​e can read gzipped files without opening them

Q2. W​hat does the line of code below do, assuming “header” is a row containing the names of each feature and “line” is a randomly picked row in a large dataset?

d = dict(zip(header, line))
  • C​onverts the line to a dictionary of key-value pairs, where each key is the name of a feature
  • L​ooks up the header in a larger dictionary and adds the line to it if missing
  • Z​ips the header and line into a single text file

Q3. W​hat does the eval() function do?

  • V​alidates and executes given Python code
  • T​ests whether the given string is valid Python code and returns true or false
  • T​reats an arbitrary string like it is Python code

Quiz 2: Simple Statistics

Q1. W​hich Python library contains the “defaultdict” structure?

  • d​ictionaries
  • c​ontainers
  • c​ollections
  • datastructures

Q2. H​ow do you get the number of items in a list?

  • l​en(list)
  • l​ist.length()
  • Lists.length(l​ist)

Q3. T​he following example is from Python’s defaultdict documentation.

from collections import defaultdict


s = 'mississippi' d = defaultdict(int) for k in s: d[k] += 1

print(d.items())

Output: dict_items([('m', 1), ('i', 4), ('s', 4), ('p', 2)])

Reset W​hat

would be the output of d[‘p’]?

  • 1​
  • 4​
  • 2​
  • 3​

quiz 3: Python: Reading Data and Simple Statistics

Q1. What are some techniques used to avoid utilizing too much memory while processing a dataset?

  • Filter data as it is being read
  • Read the data line by line
  • Use a hashtable/dictionary

Q2. What are the limitations of the CSV/TSV format?

  • It is more complicated than JSON
  • It can’t be read by Python
  • It can store only tabular data

Q3. Why is JSON a convenient data format for Python?

  • We can treat it like Python’s dictionary structure with key-value pairs
  • We can use the function eval() to easily convert a JSON file to a Python object
  • We can use JSON as a standalone Python library
  • We can treat it like Python’s list structure with its strict order and flexibility

Q4. What is the primary function of the command string.split(‘:’)?

  • Parses the string into a list of smaller strings, each originally separated by a colon
  • Finds the number of colons in the string
  • Separates and places a colon between every word in the string

Q5. What does the defaultdict() function do?

  • Automatically initializes dictionary values to existing keys
  • Convert the calling object into a copy of an existing dictionary
  • Creates a dictionary filled with random values
  • Resets an existing dictionary’s keys and values to the default Python dictionary

Q6. How would you convert a value into an int, if d is your dictionary?

  • d[‘field’] = d[‘field’].toInt()
  • d[‘field’] = d[int(‘field’)]
  • d[‘field’] = int(d[‘field’])
  • Integer.toInt(d[‘field’])

Q7. Which of the libraries below are correctly paired with what we have used them for?

  • gzip – Unzip a gzipped dataset to read it into Python
  • json – Lets you parse JSON through strings or files
  • csv – Lets you parse CSV or TSV files.
  • ast – Double-checks that the line of code to be executed is legitimate Python

Q8. W​hat is the output of the code below?

  • string = “seller_id, product_id, price, customer_id, review_id”
    string.split()
  • ‘seller_id,’, ‘product_id,’, ‘price,’, ‘customer_id,’, ‘review_id,’
  • [​’seller_id’, ‘product_id’, ‘price’, ‘customer_id’, ‘review_id’]
  • [​’seller_id,’, ‘product_id,’, ‘price,’, ‘customer_id,’, ‘review_id,’]
  • ‘seller_id’ ‘product_id’ ‘price’ ‘customer_id’ ‘review_id’

Q9. T​he following two questions involve writing a function (or method) in Python.
If you are new to functions in Python or in general, take a quick look at this page first and read over the following. Y​ou should also be somewhat familiar with the concept of loops and iterating through lists and other data structures. If not, please take a second to review the resources in Week 1.

If you feel comfortable with programming, feel free to skip over the rest of the text, click the answer choice below, and continue to questions 10 and 11.

Y​ou can identify a function in Python with the following syntax. Y​ou may have seen this in previous lectures or notebooks. Feel free to review these materials at this point.

Defining a function

def function_name( optional_parameters ):
# Code to execute when the function is called
# Optional return statements

Calling a function

function_name(optional_parameters)
d​ef – this is the keyword that starts all functions in Python.

f​unction_name – this is how you will call your function later. Make sure it’s descriptive!

o​ptional_parameters – this is the list of inputs for your function. Note that in Python, you do not have to declare the types (e.g. string, int, char, etc.) of the parameters!

E​nd your method header with a colon (:).

Here is an example of a simple function that prints out text and returns the original parameter.

Defining a function

def print_words( string ):
print(string)
return string

Calling a function

funstring = print_words( “Hello world” )
T​he output of the above will be a single “Hello world” printed on the console. funstring will point to the string object “Hello world”.

N​ote that the parameters are local to the function itself. If you have the code below, you would run into an error since the compiler cannot find the variable string outside the function.

Defining a function

def print_words( string ):
print(string)
return string

Calling a function

funstring = print_words( “Hello world” )
print(string)
Reset
1 point

I​ understand, let’s do this!

Q10. N​ote: If you are new to functions in Python, take a quick look at this page first.
Write a function named listavg that takes a numeric list as input and returns the average of the list. You do not have to check for edge cases (e.g. null list, extreme values, non-numeric values, etc.).

M​ethod Header

Y​ou can copy and paste this to start your function below.

def listavg(list_of_nums):
T​est Cases

Input

O​utput

[​1, 2, 3, 4, 5]

3​

[​ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]

1​

[​-1, 1, 0]

0​

[​0.5, 0.6, 0.7]

0​.6

Reset

Q11. N​ote: If you are new to functions in Python, take a quick look at this page first.
Write a function named count_data that takes a complete “dataset” and string as input. It returns a defaultdict object containing the count of content in the given dataset’s column.

You do not have to check for edge cases. Review the lecture “Extracting Simple Statistics From Datasets” and its Review Quiz for a refresher on defaultdict and a hint on getting the count of items in a column.

Parameters
d​ataset – This dataset is a list of key-value pairs, as shown in the lecture “Processing Structured Data in Python”. See the Example Dataset below.

f​ield – This is your key, a string of the name of the field we want to examine.

You can use a key t​o access a single value of the dataset by iterating through the rows of the dataset.

As an example, the keys might be [‘star_rating’, ‘business_name’, ‘location’], while a single row in the dataset might look like [4, ‘Starbucks’, ‘123 Main Street, Townsville’] where each value corresponds to a key.

row42[‘star_rating’] would result in the integer 4, following the example above.

Example Dataset
N​ote that the dataset will be randomized, so you will likely not get the exact values and strings below. T​hese are trivial examples and the test dataset will be larger than the one shown below.

count_data(dataset, ‘​star_rating’)–> defaultdict(int, {​1: 1, 2: 1, 4: 2, 5: 1})

count_data(dataset, ‘​answer_key’) –> defaultdict(int, {True: 3, False: 2})

count_data(dataset, ‘​units_sold’) –> defaultdict(int, {5: 1, 119: 1, 223: 1, 456: 1, 2003: 1})

star_rating

answer_key

units_sold

1​

T​rue

119

4​

T​rue

2003

5​

F​alse

5​

2​

T​rue

456

4​

F​alse

2​23

G​etting Started
C​reate a defaultdict object to hold integer counts. This is what we will return. The keys will be the unique values of the column; for ‘star_rating’, you might have 5 integer keys (1, 2, 3, 4, and 5). The values will be the number of times each unique key appears in the column.

I​terate through the rows of the dataset.

F​or each row, first determine the key to add to the defaultdict object (i.e. the element in the given field). Review Parameters above if you need a hint on how to get the correct key for the defaultdict object.

N​ow that you have your key, increment the corresponding value in the defaultdict object by 1.

After you have processed all rows, r​eturn the defaultdict object.

M​ethod Header
Y​ou can copy and paste this to start your function below.

def count_data(dataset, field):

from collections import defaultdict
Reset

Week 3 Quiz Answers

Quiz 1: Review: Data Filtering and Cleaning

Q1. W​hat are some reasons for cleaning or “pre-processing” datasets?

  • S​ome entries might be poorly formatted
  • S​ome parts of the dataset might have significant outliers
  • F​ields might be missing from some entries
  • S​ome data may need to be restricted to certain groups
  • S​ome parts of the dataset might be “stale” (outdated in a sense)
  • S​ome data may apply to only rare or inactive users

Q2. H​ow might we filter a list of businesses based on their ratings and number of reviews? Assume “dataset” contains a complete cleaned dataset of businesses and relevant features.


if dataset['rating'] > 3.5 and dataset['num_reviews'] == 20:
    dataset = [d for d in dataset] 

if d['rating'] > 3.5 and d['num_reviews'] == 20:
    dataset = [d for d in dataset] 


dataset = [d for d in dataset if d['rating'] > 3.5] and [d['num_reviews'] == 20]


dataset = [d for d in dataset if d['rating'] > 3.5 and d['num_reviews'] == 20]

Q3. W​hat are some ways we can filter reviews by?

  • R​eview rating
  • U​ser activity
  • User location
  • R​eview length
  • R​eview quality
  • D​ate

Quiz 2: Review: Processing Different Data Types

Q1. What is tokenization (in the context of this module)?

  • T​he act of replacing each discrete “token” of a string with user-defined tokens
  • T​he act of putting together several discrete “tokens” into one string
  • The act of splitting a string into dicrete “tokens” by a defined delimiter

Q2. W​hen would strptime() be convenient?

  • W​hen we want to extract features from data
  • W​hen we want to convert a time object to a string
  • W​hen we want to directly numerically compare times

Q3. W​hat is the output of the code below?

string = ['hello', 'mam', 'why']
', '.join(string)
  • “​hellomamwhy”
  • “​hello mam why”
  • “​hello,mam,why”
  • “​hello, mam, why”

Q4. W​hich libraries are useful for processing time data?

  • c​alendar
  • d​atetime
  • c​lock
  • t​ime

Quiz 3: Data Processing in Python

Q1. What is the meaning of a “KeyError”?

  • The requested key is missing from the dictionary object
  • The requested key does not have a corresponding value
  • The requested key has the wrong format

Q2. What does string.punctuation return?

  • A list of random words with interjected punctuation characters
  • A random punctuation character
  • A string of commonly-used punctuation characters

Q3. Why are case-changing string commands like string.upper() or string.lower() useful?

  • We can more easily compare different variations of the same word, like APPle and appLE
  • We don’t have to iterate character-by-character to convert a word to upper or lowercase
  • Computing statistics on text is easier when we don’t care about word case.

Q4. What is Unix time?

  • A secret timezone embedded in all computer systems
  • The number of seconds since January 1, 1970, in the UTC timezone
  • A countdown to when all 32-bit systems will overflow

Q5. What is true about Time.strptime?

We can more easily extract features from data

  • It converts a structured time object to a number
  • It converts a number to a structured time object
  • It converts a time string to a structured time object
  • It converts a structured time object to a time string

Q6. What is the difference between mktime() and gmtime()?

  • For the given time struct, mktime() assumes it is local time, gmtime() assumes it is UTC time.
  • There is no difference.
  • For the given time struct, mktime() assumes it is UTC time, gmtime() assumes it is local time.

Q7. Write a function named string_processing that takes a list of strings as input and returns an all-lowercase string with no punctuation.

There should be a space between each word. You do not have to check for edge cases.

M​ethod Header

def string_processing(string_list):
T​est Cases

Input

Output

[​’hello,’, ‘world!’]

‘​hello world’

[​’test…’, ‘me….’, ‘please’]

‘​test me please’

import string

Week 4 Quiz Answers

Quiz 1: Review: NumPy

Q1. W​hy might we want to use numpy.matrix() instead of numpy.array() or numpy.stack()?

  • W​e are performing complex mathematical expressions with matrices
  • W​e should never use numpy.matrix(); a matrix is just a multi-dimensional array
  • W​e should always use numpy.matrix() since it is faster than numpy.stack() or numpy.array()
  • We are multiplying matrices together

Q2. W​hat is the output of the code below?

import numpy
numpy.eye(3)
  • [[3 3 3]
    [3 3 3]
    [3 3 3]
  • [[ 0. 0. 0.]
    [ 0. 1. 0.]
    [ 0. 0. 0.]]
  • [[1 0 0]
    [0 1 0]
    [0 0 1]]
  • [[ 1. 0. 0.]
    [ 0. 1. 0.]
    [ 0. 0. 1.]]
  • [[3 0 0]
    [0 3 0]
    [0 0 3]

Quiz 2: Review: MatPlotLib

Q1. H​ow do you change the name of a library you are working with in Python?

  • from name import library
  • import library as name
  • import library
    name = python.renamelib(library)

Q2. H​ow would you create a basic bar plot with matplotlib, given the following?

import matplotlib.pyplot as plt
X = list(features)
y = [results[x] for x in X]
  • b​arplot(plt, X, y)
  • m​atplotlib.bar(X, y)
  • p​lt.barplot(X, y)
  • p​lt.bar(X, y)

Q3. W​hich of the following are useful functions for modifying a graph in matplotlib?

  • p​lot()
  • y​label()
  • a​xis()
  • x​label()
  • l​egend()
  • t​itle()
  • y​lim()
  • y​ticks()
  • x​ticks()

Quiz 3: Review: urllib and BeautifulSoup

Q1. W​hat is the difference between urllib and BeautifulSoup?

  • u​rllib helps us get the HTML contents of a webpage, while BeautifulSoup helps us parse HTML.
  • u​rllib helps us parse HTML, while BeautifulSoup helps us get the HTML contents of a webpage.

Q2. T​rue or False: We should use BeautifulSoup to traverse any HTML page we want to parse.

  • F​alse
  • T​rue

Q3. W​hich of the following are advantages of BeautifulSoup?

  • B​eautifulSoup parses the HTML contents of a given webpage to extract desired text
  • B​eautifulSoup parses the HTML contents of an entire website given a single URL
  • B​eautifulSoup requires minimal setup to use

Quiz 4: Python Libraries and Toolkits

Q1. H​ow would you extract a single feature from a dataset with a single line of code?

feature = dataset[‘feature’] for d in dataset

feature = dataset[‘feature’]

feature = (for d in dataset: d[‘feature’])

feature = [d[‘feature’] for d in dataset]

Q2. H​ow would you build a 3D array from these features? Assume each feature is currently a list.

array = numpy.stack(
feature1,
feature2,
feature3
)
array = numpy.stack(
numpy.array(feature1),
numpy.array(feature2),
numpyarray(feature3)
)
array = numpy.array(
feature1,
feature2,
feature3
)

Q3. T​rue or False: Elements in numpy arrays must be all the same type.

  • T​rue
  • F​alse

Q4. How would you change the number 5 to 7 in this matrix?

arr = numpy.array([1,2,3,4,5])
  • arr[0,5] = 7
  • arr[5] = 7
  • arr[0,4] = 7
  • arr[4] = 7

Q5. Which command allows you to edit the view of the axes on a matlibplot plot?

  • g​rid()
  • a​xis()
  • p​lot()
  • arrange()

Q6. When is it NOT acceptable to avoid axis labels in plots using matlibplot?

  • When you are simply exploring the data and know their values.
  • When you are presenting non-intuitive results to another person.
  • When the labels can be determined by the values (e.g., percentage correct, years).

Q7. Which graphing method should you use to visualize the correlation between two arrays?

  • S​catterplot
  • B​ox plot
  • H​istogram
  • L​ine plot
  • B​ar plot
Conclusion:

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