3.2 Algorithms
by Paul J. Deitel,
Harvey M. Deitel
Intro to Python for Computer Science and Data Science: Learning to Program with AI, Big Data and The Cloud
- Intro to Python® for Computer Science and Data Science
- Deitel® Series Page
- Intro to Python® for Computer Science and Data Science
- Intro to Python® for Computer Science and Data Science
- Contents
- 1 Introduction to Computers and Python
- Objectives
- Outline
- 1.1 Introduction
- 1.2 Hardware and Software
- 1.3 Data Hierarchy
- 1.4 Machine Languages, Assembly Languages and High-Level Languages
- 1.5 Introduction to Object Technology
- 1.6 Operating Systems
- 1.7 Python
- 1.8 It’s the Libraries!It’s the Libraries!
- 1.9 Other Popular Programming Languages
- 1.10 Test-Drive: Using IPython and Jupyter Notebooks
- 1.10.1 Using IPython Interactive Mode as a Calculator
- Self Check
- 1.10.2 Executing a Python Program Using the IPython Interpreter
- Self Check
- 1.10.3 Writing and Executing Code in a Jupyter Notebook
- Opening JupyterLab in Your Browser
- Creating a New Jupyter Notebook
- Renaming the Notebook
- Evaluating an Expression
- Adding and Executing Another Cell
- Saving the Notebook
- Notebooks Provided with Each Chapter’s Examples
- Opening and Executing an Existing Notebook
- Closing JupyterLab
- JupyterLab Tips
- More Information on Working with JupyterLab
- Self Check
- 1.11 Internet and World Wide Web
- 1.13 How Big Is Big Data?
- 1.15 Intro to Data Science: Artificial Intelligence—at the Intersection of CS and Data ScienceIntro to Data Science: Artificial Intelligence—at the Intersection of CS and Data Science
- Exercises
- 2 Introduction to Python Programming
- 2.5 Triple-Quoted Strings
- 2.6 Getting Input from the User
- 2.7 Decision Making: The if Statement and Comparison Operators
- 2.8 Objects and Dynamic Typing
- 2.9 Intro to Data Science: Basic Descriptive Statistics
- 2.10 Wrap-Up
- Exercises
- 3 Control Statements and Program Development
- Objectives
- Outline
- 3.1 Introduction
- 3.2 Algorithms
- 3.3 Pseudocode
- 3.4 Control Statements
- 3.5 if Statement
- 3.6 if……else and if……elif……else Statements
- 3.7 while Statement
- 3.8 for Statement
- 3.9 Augmented Assignments
- 3.10 Program Development: Sequence-Controlled Repetition
- 3.11 Program Development: Sentinel-Controlled Repetition
- 3.12 Program Development: Nested Control Statements
- 3.13 Built-In Function range: A Deeper Look
- 3.14 Using Type Decimal for Monetary Amounts
- 3.15 break and continue Statements
- 3.16 Boolean Operators and, or and not
- 3.17 Intro to Data Science: Measures of Central Tendency—Mean, Median and ModeIntro to Data Science: Measures of Central Tendency—Mean, Median and Mode
- 3.18 Wrap-Up
- Exercises
- 4 Functions
- Objectives
- Outline
- 4.1 Introduction
- 4.2 Defining Functions
- 4.3 Functions with Multiple Parameters
- 4.4 Random-Number Generation
- 4.5 Case Study: A Game of Chance
- 4.6 Python Standard Library
- 4.7 math Module Functions
- 4.8 Using IPython Tab Completion for Discovery
- 4.9 Default Parameter Values
- 4.10 Keyword Arguments
- 4.11 Arbitrary Argument Lists
- 4.12 Methods: Functions That Belong to Objects
- 4.13 Scope Rules
- 4.14 import: A Deeper Look
- 4.15 Passing Arguments to Functions: A Deeper Look
- 4.16 Function-Call Stack
- 4.17 Functional-Style Programming
- 4.18 Intro to Data Science: Measures of Dispersion
- 4.19 Wrap-Up
- Exercises
- 5 Sequences: Lists and Tuples
- Objectives
- Outline
- 5.1 Introduction
- 5.2 Lists
- 5.3 Tuples
- 5.4 Unpacking Sequences
- 5.5 Sequence Slicing
- 5.6 del Statement
- 5.7 Passing Lists to Functions
- 5.8 Sorting Lists
- 5.9 Searching Sequences
- 5.10 Other List Methods
- 5.11 Simulating Stacks with Lists
- 5.12 List Comprehensions
- 5.13 Generator Expressions
- 5.14 Filter, Map and Reduce
- 5.15 Other Sequence Processing Functions
- 5.16 Two-Dimensional Lists
- 5.17 Intro to Data Science: Simulation and Static Visualizations
- 5.17.1 Sample Graphs for 600, 60,000 and 6,000,000 Die Rolls
- Self Check
- 5.17.2 Visualizing Die-Roll Frequencies and Percentages
- Launching IPython for Interactive Matplotlib Development
- Importing the Libraries
- Rolling the Die and Calculating Die Frequencies
- Creating the Initial Bar Plot
- Setting the Window Title and Labeling the x- and y-Axes
- Finalizing the Bar Plot
- Rolling Again and Updating the Bar Plot—Introducing IPython Magics
- Saving Snippets to a File with the %save Magic
- Command-Line Arguments; Displaying a Plot from a Script
- Self Check
- 5.18 Wrap-Up
- Exercises
- 6 Dictionaries and Sets
- Objectives
- Outline
- 6.1 Introduction
- 6.2 Dictionaries
- 6.2.1 Creating a Dictionary
- 6.2.2 Iterating through a Dictionary
- Self Check
- 6.2.3 Basic Dictionary Operations
- Self Check
- 6.2.4 Dictionary Methods keys and values
- Self Check
- 6.2.5 Dictionary Comparisons
- Self Check
- 6.2.6 Example: Dictionary of Student Grades
- 6.2.7 Example: Word Counts2
- Self Check
- 6.2.8 Dictionary Method update
- Self Check
- 6.3 Sets
- 6.4 Intro to Data Science: Dynamic Visualizations
- Self Check
- 6.4.1 How Dynamic Visualization Works
- Self Check
- 6.4.2 Implementing a Dynamic Visualization
- Importing the Matplotlib animation Module
- Function update
- Function update: Rolling the Die and Updating the frequencies List
- Function update: Configuring the Bar Plot and Text
- Variables Used to Configure the Graph and Maintain State
- Calling the animation Module’s Module’s FuncAnimation Function
- Self Check
- 6.5 Wrap-Up
- Exercises
- 7 Array-Oriented Programming with NumPy
- Objectives
- Outline
- 7.1 Introduction
- 7.2 Creating arrays from Existing Data
- 7.3 array Attributes
- 7.4 Filling arrays with Specific Values
- 7.5 Creating arrays from Ranges
- 7.6 List vs. array Performance: Introducing %timeit
- 7.7 array Operators
- 7.8 NumPy Calculation Methods
- 7.9 Universal Functions
- 7.10 Indexing and Slicing
- 7.11 Views: Shallow Copies
- 7.12 Deep Copies
- 7.13 Reshaping and Transposing
- 7.14 Intro to Data Science: pandas Series and DataFrames
- 7.14.1 pandas Series
- Creating a Series with Default Indices
- Displaying a Series
- Creating a Series with All Elements Having the Same Value
- Accessing a Series’ Elements’ Elements
- Producing Descriptive Statistics for a Series
- Creating a Series with Custom Indices
- Dictionary Initializers
- Accessing Elements of a Series Via Custom Indices
- Creating a Series of Strings
- Self Check
- 7.14.2 DataFrames
- Creating a DataFrame from a Dictionary
- Customizing a DataFrame’s Indices with the ’s Indices with the index Attribute
- Accessing a DataFrame’s Columns ’s Columns
- Selecting Rows via the loc and iloc Attributes
- Selecting Rows via Slices and Lists with the loc and iloc Attributes
- Selecting Subsets of the Rows and Columns
- Boolean Indexing
- Accessing a Specific DataFrame Cell by Row and Column
- Descriptive Statistics
- Transposing the DataFrame with the T Attribute
- Sorting by Rows by Their Indices
- Sorting by Column Indices
- Sorting by Column Values
- Copy vs. In-Place Sorting
- Self Check
- 7.14.1 pandas Series
- 7.15 Wrap-Up
- Exercises
- 8 Strings: A Deeper Look
- Objectives
- Outline
- 8.1 Introduction
- 8.2 Formatting Strings
- 8.2.1 Presentation Types
- Integers
- Characters
- Strings
- Floating-Point and Decimal Values
- Self Check
- 8.2.2 Field Widths and Alignment
- Explicitly Specifying Left and Right Alignment in a Field
- Centering a Value in a Field
- Self Check
- 8.2.3Numeric Formatting
- Formatting Positive Numbers with Signs
- Using a Space Where a + Sign Would Appear in a Positive Value
- Grouping Digits
- Self Check
- 8.2.4String’s String’s format Method
- Multiple Placeholders
- Referencing Arguments By Position Number
- Referencing Keyword Arguments
- Self Check
- 8.3 Concatenating and Repeating Strings
- 8.4 Stripping Whitespace from Strings
- 8.5 Changing Character Case
- 8.6 Comparison Operators for Strings
- 8.7 Searching for Substrings
- 8.8 Replacing Substrings
- 8.9 Splitting and Joining Strings
- 8.10 Characters and Character-Testing Methods
- 8.11 Raw Strings
- 8.12 Introduction to Regular Expressions
- 8.12.1 re Module and Function fullmatch
- 8.12.2 Replacing Substrings and Splitting Strings
- 8.12.3 Other Search Functions; Accessing Matches
- Function search—Finding the First Match Anywhere in a String—Finding the First Match Anywhere in a String
- Ignoring Case with the Optional flags Keyword Argument
- Metacharacters That Restrict Matches to the Beginning or End of a String
- Function findall and finditer—Finding All Matches in a String—Finding All Matches in a String
- Capturing Substrings in a Match
- Self Check
- 8.13 Intro to Data Science: Pandas, Regular Expressions and Data Munging
- 8.14 Wrap-Up
- Exercises
- 9 Files and Exceptions
- Objectives
- Outline
- 9.1 Introduction
- 9.2 Files
- 9.3 Text-File Processing
- 9.4 Updating Text Files
- 9.5 Serialization with JSON
- 9.6 Focus on Security: pickle Serialization and Deserialization
- 9.7 Additional Notes Regarding Files
- 9.8 Handling Exceptions
- 9.9 finally Clause
- 9.10 Explicitly Raising an Exception
- 9.11 (Optional) Stack Unwinding and Tracebacks
- 9.12 Intro to Data Science: Working with CSV Files
- 9.13 Wrap-Up
- Exercises
- 10 Object-Oriented Programming
- Objectives
- Outline
- 10.1 Introduction
- 10.2 Custom Class Account
- 10.3 Controlling Access to Attributes
- 10.4 Properties for Data Access
- 10.5 Simulating “Private” AttributesSimulating “Private” Attributes
- 10.6 Case Study: Card Shuffling and Dealing Simulation
- 10.7 Inheritance: Base Classes and Subclasses
- 10.8 Building an Inheritance Hierarchy; Introducing Polymorphism
- 10.9 Duck Typing and Polymorphism
- 10.10 Operator Overloading
- 10.11 Exception Class Hierarchy and Custom Exceptions
- 10.12 Named Tuples
- 10.13 A Brief Intro to Python 3.7’s New Data ClassesA Brief Intro to Python 3.7’s New Data Classes
- 10.14 Unit Testing with Docstrings and doctest
- 10.15 Namespaces and Scopes
- 10.16 Intro to Data Science: Time Series and Simple Linear Regression
- 10.17 Wrap-Up
- Exercises
- 11 Computer Science Thinking: Recursion, Searching, Sorting and Big O
- Objectives
- Outline
- 11.1 Introduction
- 11.2 Factorials
- 11.3 Recursive Factorial Example
- 11.4 Recursive Fibonacci Series Example
- 11.5 Recursion vs. Iteration
- 11.6 Self Check
- 11.6 Searching and Sorting
- 11.7 Linear Search
- 11.8 Efficiency of Algorithms: Big O
- 11.9 Binary Search
- 11.10 Sorting Algorithms
- 11.11 Selection Sort
- 11.12 Insertion Sort
- 11.13 Merge Sort
- 11.14 Big O Summary for This Chapter’s Searching and Sorting AlgorithmsBig O Summary for This Chapter’s Searching and Sorting Algorithms
- 11.15 Visualizing Algorithms
- 11.16 Wrap-Up
- Exercises
- 12 Natural Language Processing (NLP)
- Objectives
- Outline
- 12.1 Introduction
- 12.2 TextBlob1
- Self Check
- 12.2.1 Create a TextBlob
- Self Check
- 12.2.2 Tokenizing Text into Sentences and Words
- Self Check
- 12.2.3 Parts-of-Speech Tagging
- Self Check
- 12.2.4 Extracting Noun Phrases
- Self Check
- 12.2.5 Sentiment Analysis with TextBlob’s Default Sentiment AnalyzerSentiment Analysis with TextBlob’s Default Sentiment Analyzer
- Self Check
- 12.2.6 Sentiment Analysis with the NaiveBayesAnalyzer
- Self Check
- 12.2.7 Language Detection and Translation
- Self Check
- 12.2.8 Inflection: Pluralization and Singularization
- Self Check
- 12.2.9 Spell Checking and Correction
- Self Check
- 12.2.10 Normalization: Stemming and Lemmatization
- Self Check
- 12.2.11 Word Frequencies
- Self Check
- 12.2.12 Getting Definitions, Synonyms and Antonyms from WordNet
- Self Check
- 12.2.13 Deleting Stop Words
- Self Check
- 12.2.14 n-grams
- Self Check
- 12.3 Visualizing Word Frequencies with Bar Charts and Word Clouds
- 12.4 Readability Assessment with Textatistic
- 12.5 Named Entity Recognition with spaCy
- 12.6 Similarity Detection with spaCy
- 12.7 Other NLP Libraries and Tools
- 12.8 Machine Learning and Deep Learning Natural Language Applications
- 12.9 Natural Language Datasets
- 12.10 Wrap-Up
- Exercises
- 13 Data Mining Twitter
- Objectives
- Outline
- 13.1 Introduction
- 13.2 Overview of the Twitter APIs
- 13.3 Creating a Twitter Account
- 13.4 Getting Twitter Credentials—Creating an AppGetting Twitter Credentials—Creating an App
- 13.5 What’s in a Tweet?What’s in a Tweet?
- 13.6 Tweepy
- 13.7 Authenticating with Twitter Via Tweepy
- 13.8 Getting Information About a Twitter Account
- 13.9 Introduction to Tweepy Cursors: Getting an Account’s Followers and Friendss: Getting an Account’s Followers and Friends
- 13.10 Searching Recent Tweets
- 13.11 Spotting Trends: Twitter Trends API
- 13.12 Cleaning/Preprocessing Tweets for Analysis
- 13.13 Twitter Streaming API
- 13.14 Tweet Sentiment Analysis
- 13.15 Geocoding and Mapping
- Self Check
- 13.15.1 Getting and Mapping the Tweets
- Get the API Object
- Collections Required By LocationListener
- Creating the LocationListener
- Configure and Start the Stream of Tweets
- Displaying the Location Statistics
- Geocoding the Locations
- Displaying the Bad Location Statistics
- Cleaning the Data
- Creating a Map with Folium
- Creating Popup Markers for the Tweet Locations
- Saving the Map
- Self Check
- 13.15.2 Utility Functions in tweetutilities.py
- Self Check
- 13.15.3 Class LocationListener
- 13.16 Ways to Store Tweets
- 13.17 Twitter and Time Series
- 13.18 Wrap-Up
- Exercises
- 14 IBM Watson and Cognitive Computing
- Outline
- 14.1 Introduction: IBM Watson and Cognitive Computing
- 14.2 IBM Cloud Account and Cloud Console
- 14.3 Watson Services
- 14.4 Additional Services and Tools
- 14.5 Watson Developer Cloud Python SDK
- 14.6 Case Study: Traveler’s Companion Translation AppCase Study: Traveler’s Companion Translation App
- 14.7 Watson Resources
- 14.8 Wrap-Up
- Exercises
- 15 Machine Learning: Classification, Regression and Clustering
- Outline
- 15.1 Introduction to Machine Learning
- 15.2 Case Study: Classification with k-Nearest Neighbors and the Digits Dataset, Part 1
- 15.3 Case Study: Classification with k-Nearest Neighbors and the Digits Dataset, Part 2
- 15.4 Case Study: Time Series and Simple Linear Regression
- 15.5 Case Study: Multiple Linear Regression with the California Housing Dataset
- 15.5.1 Loading the Dataset
- 15.5.2 Exploring the Data with Pandas
- Self Check
- 15.5.3 Visualizing the Features
- Self Check
- 15.5.4 Splitting the Data for Training and Testing
- 15.5.5 Training the Model
- Self Check
- 15.5.6 Testing the Model
- 15.5.7 Visualizing the Expected vs. Predicted Prices
- 15.5.8 Regression Model Metrics
- Self Check
- 15.5.9 Choosing the Best Model
- 15.6 Case Study: Unsupervised Machine Learning, Part 1—Dimensionality ReductionCase Study: Unsupervised Machine Learning, Part 1—Dimensionality Reduction
- 15.7 Case Study: Unsupervised Machine Learning, Part 2—k-Means ClusteringCase Study: Unsupervised Machine Learning, Part 2—k-Means Clustering
- Self Check
- 15.7.1 Loading the Iris Dataset
- 15.7.2 Exploring the Iris Dataset: Descriptive Statistics with Pandas
- 15.7.3 Visualizing the Dataset with a Seaborn pairplot
- 15.7.4 Using a KMeans Estimator
- 15.7.5 Dimensionality Reduction with Principal Component Analysis
- 15.7.6 Choosing the Best Clustering Estimator
- 15.8 Wrap-Up
- Exercises
- 16 Deep Learning
- Objectives
- Outline
- 16.1 Introduction
- 16.2 Keras Built-In Datasets
- 16.3 Custom Anaconda Environments
- 16.4 Neural Networks
- 16.5 Tensors
- 16.6 Convolutional Neural Networks for Vision; Multi-Classification with the MNIST Dataset
- Self Check
- 16.6.1 Loading the MNIST Dataset
- Self Check
- 16.6.2 Data Exploration
- 16.6.3 Data Preparation
- Self Check
- 16.6.4 Creating the Neural Network
- Adding Layers to the Network
- Convolution
- Adding a Convolution Layer
- Dimensionality of the First Convolution Layer’s Output
- Overfitting
- Adding a Pooling Layer
- Adding Another Convolutional Layer and Pooling Layer
- Flattening the Results
- Adding a Dense Layer to Reduce the Number of Features
- Adding Another Dense Layer to Produce the Final Output
- Printing the Model’s Summary
- Visualizing a Model’s Structure
- Compiling the Model
- Self Check
- 16.6.5 Training and Evaluating the Model
- Self Check
- 16.6.6 Saving and Loading a Model
- Self Check
- 16.7 Visualizing Neural Network Training with TensorBoard
- 16.8 ConvnetJS: Browser-Based Deep-Learning Training and Visualization
- 16.9 Recurrent Neural Networks for Sequences; Sentiment Analysis with the IMDb Dataset
- 16.10 Tuning Deep Learning Models
- 16.11 Convnet Models Pretrained on ImageNet
- 16.12 Reinforcement Learning
- 16.13 Wrap-Up
- Exercises
- Convolutional Neural Networks
- Recurrent Neural Networks
- ConvnetJS Visualization
- Convolutional Neural Network Projects and Research
- Recurrent Neural Network Projects and Research
- Automated Deep Learning Project
- Reinforcement Learning Projects and Research
- Generative Deep Learning
- Deep Fakes
- Additional Research
- 17 Big Data: Hadoop, Spark, NoSQL and IoT
- Objectives
- Outline
- 17.1 Introduction
- 17.2 Relational Databases and Structured Query Language (SQL)
- 17.3 NoSQL and NewSQL Big-Data Databases: A Brief Tour
- 17.4 Case Study: A MongoDB JSON Document Database
- 17.4.1 Creating the MongoDB Atlas Cluster
- 17.4.2 Streaming Tweets into MongoDB
- Use Tweepy to Authenticate with Twitter
- Loading the Senators’ Data
- Configuring the MongoClient
- Setting up Tweet Stream
- Starting the Tweet Stream
- Class TweetListener
- Counting Tweets for Each Senator
- Show Tweet Counts for Each Senator
- Get the State Locations for Plotting Markers
- Grouping the Tweet Counts by State
- Creating the Map
- Creating a Choropleth to Color the Map
- Creating the Map Markers for Each State
- Displaying the Map
- Self Check for Section 17.4
- 17.5 Hadoop
- 17.5.1 Hadoop Overview
- 17.5.2 Summarizing Word Lengths in Romeo and Juliet via MapReduce
- 17.5.3 Creating an Apache Hadoop Cluster in Microsoft Azure HDInsight
- 17.5.4 Hadoop Streaming
- 17.5.5 Implementing the Mapper
- 17.5.6 Implementing the Reducer
- 17.5.7 Preparing to Run the MapReduce Example
- 17.5.8 Running the MapReduce Job
- Self Check for Section 17.5
- 17.6 Spark
- 17.7 Spark Streaming: Counting Twitter Hashtags Using the pyspark-notebook Docker Stack
- 17.7.1 Streaming Tweets to a Socket
- 17.7.2 Summarizing Tweet Hashtags; Introducing Spark SQL
- Importing the Libraries
- Utility Function to Get the SparkSession
- Utility Function to Display a Barchart Based on a Spark DataFrame
- Utility Function to Summarize the Top-20 Hashtags So Far
- Getting the SparkContext
- Getting the StreamingContext
- Setting Up a Checkpoint for Maintaining State
- Connecting to the Stream via a Socket
- Tokenizing the Lines of Hashtags
- Mapping the Hashtags to Tuples of Hashtag-Count Pairs
- Totaling the Hashtag Counts So Far
- Specifying the Method to Call for Every RDD
- Starting the Spark Stream
- Self Check for Section 17.7
- 17.8 Internet of Things and Dashboards
- 17.8.1 Publish and Subscribe
- 17.8.2 Visualizing a PubNub Sample Live Stream with a Freeboard Dashboard
- 17.8.3 Simulating an Internet-Connected Thermostat in Python
- 17.8.4 Creating the Dashboard with Freeboard.io
- 17.8.5 Creating a Python PubNub Subscriber
- Message Format
- Importing the Libraries
- List and DataFrame Used for Storing Company Names and Prices
- Class SensorSubscriberCallback
- Function Update
- Configuring the Figure
- Configuring the FuncAnimation and Displaying the Window
- Configuring the PubNub Client
- Subscribing to the Channel
- Ensuring the Figure Remains on the Screen
- Self Check for Section 17.8
- 17.9 Wrap-Up
- Exercises
- Index
3.2 Algorithms
You can solve any computing problem by executing a series of actions in a specific order. An algorithm is a procedure for solving a problem in terms of:
the actions to execute, and
the order in which these actions execute.
Correctly specifying the order in which the actions execute is essential. Consider the “rise-and-shine algorithm” that an executive follows for getting out of bed and going to work: (1) Get out of bed; (2) take off pajamas; (3) take a shower; (4) get dressed; (5) eat breakfast; (6) carpool to work. This routine gets the executive to work well prepared to make critical decisions. Suppose the executive performs these steps in a different order: (1) Get out of bed; (2) take off pajamas; (3) get dressed; (4) take a shower; (5) eat breakfast; (6) carpool to work. Now, our executive shows up for work soaking wet. Program control specifies the order in which statements (actions) execute in a program. This chapter investigates program control using Python’s control statements.
Self Check
(Fill-In) A(n) ___________ is a procedure for solving a problem. It specifies the ___________ to execute and the ___________ in which they execute.
Answer: algorithm, actions, order.
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