The Python Apprentice by Smallshire, Robert -- Read -- Imperial Library of Trantor

Index

Preface

Python Promo Overview What is Python?

It's a standard library! It's a philosophy

The journey of a thousand miles… Errata and Suggestions Conventions Used in This Book Downloading the example code Downloading the color images of this book

Getting started

Obtaining and installing Python 3

Windows macOS Linux

Starting Python command line REPL Leaving the REPL

Windows Unix

Code structure and significant indentation Python culture Importing standard library modules Getting help()

Counting fruit with math.factorial() Different types of numbers

Scalar data types: integers, floats, None and bool

int float

Special floating point values Promotion to float

None bool

Relational operators

Rich comparison operators

Control flow: if-statements and while-loops

Conditional control flow: The if-statement if...else if...elif...else Conditional repetition: the while-loop

Exiting loops with break

Summary

Strings and Collections

str – an immutable sequence of Unicode code points

String quoting styles

Moment of zen

Concatenation of adjacent strings Multiline strings and newlines Raw strings

The str constructor

Strings as sequences String methods

Strings with Unicode The bytes type – an immutable sequence of bytes

Literal bytes Converting between bytes and str

list – a sequence of objects The dict type – associating keys with values The For-loops – iterating over series of items Putting it all together Summary

Modularity

Organizing code in a .py file

Running Python programs from the operating system shell Importing modules into the REPL

Defining functions Organizing our module into functions

The __name__ type and executing modules from the command line

The Python execution model

The difference between modules, scripts, and programs

Setting up a main function with command line argument

Accepting command line arguments

Moment of zen Docstrings Comments Shebang

Executable Python programs on Linux and Mac Executable Python programs on Windows Summary

Built-in types and the object model

The nature of Python object references

Reassigning a reference Assigning one reference to another Exploring value vs. identity with id() Testing for equality of identity with is Mutating without mutating References to mutable objects Equality of value (equivalence) versus equality of identity

Argument passing semantics – pass by object-reference

Modifying external objects in a function Binding new objects in a function Argument passing is reference binding

Python return semantics Function arguments in detail

Default parameter values Keyword arguments When are default arguments evaluated?

The Python type system

Dynamic typing in Python Strong typing in Python

Variable declaration and scoping

The LEGB rule

Scopes in action

Identical names in global and local scope The global keyword

Moment of zen Everything is an object

Inspecting a function

Summary

Exploring Built-in Collection types

tuple – an immutable sequence of objects

Literal tuples Tuple element access

The length of a tuple

Iterating over a tuple Concatenating and repetition of tuples

Nested tuples

Single-element tuples Empty tuples Optional parentheses Returning and unpacking tuples Swapping variables with tuple unpacking

The tuple constructor

Membership tests

Strings in action

The length of a string Concatenating strings Joining strings Splitting strings

Moment of zen

Partitioning strings String formatting Other string methods

range – a collection of evenly spaced integers

Starting value Step argument Not using range: enumerate()

list in action

Negative indexing for lists (and other sequences) Slicing lists Copying lists Shallow copies Repeating lists Finding list elements with index() Membership testing with count() and in Removing list elements by index with del Removing list elements by value with remove() Inserting into a list Concatenating lists Rearranging list elements Out-of-place rearrangement

Dictionaries

Copying dictionaries Updating dictionaries Iterating over dictionary keys Iterating over dictionary values Iterating over key-value pairs Membership testing for dictionary keys Removing dictionary items Mutability of dictionaries Pretty printing

set – an unordered collection of unique elements

The set constructor Iterating over sets Membership testing of sets Adding elements to sets Removing elements from sets Copying sets Set algebra operations Union

Intersection

Difference

Symmetric difference Subset relationships

Collection protocols

Container protocol Sized protocol Iterable protocol Sequence protocol Other protocols

Summary

Exceptions

Exceptions and control flow

Handling exceptions

Handling multiple exceptions Programmer errors Empty blocks – the pass statement Exception objects Imprudent return codes Re-raising exceptions Exceptions are part of your function's API

Exceptions raised by Python Catching exceptions Raising exceptions explicitly

Guard clauses Exceptions, APIs, and protocols

IndexError ValueError KeyError

Choosing not to guard against TypeError Pythonic style – EAFP versus LBYL Clean-up actions Moment of zen Platform-specific code Summary

Comprehensions, iterables, and generators

Comprehensions

List comprehensions

List comprehension syntax Elements of a list comprehension

Set comprehensions Dictionary comprehensions

Comprehension complexity

Filtering comprehensions

Combining filtering and transformation

Moment of zen Iteration protocols

An example of the iteration protocols A more practical example of the iteration protocols

Generator functions

The yield keyword Generators are iterators When is generator code executed? Maintaining explicit state in the generator function

The first stateful generator: take() The second stateful generator: distinct() Understand these generators! Lazy generator pipelines

Laziness and the infinite

Generating the Lucas series

Generator expressions Batteries included iteration tools

Introducing itertools Sequences of booleans Merging sequences with zip

More than two sequences with zip()

Lazily concatenating sequences with chain()

Pulling it all together Summary

Generators Iteration tools

Defining new types with classes

Defining classes Instance methods Instance initializers

A lack of access modifiers

Validation and invariants Adding a second class Collaborating classes Moment of zen Booking seats

Allocating seats to passengers

Naming methods for implementation details

Implementing relocate_passenger() Counting available seats

Sometimes the only object you need is a function

Making Flight create boarding cards

Polymorphism and duck-typing

Refactoring Aircraft

Inheritance and implementation sharing

A base class for aircraft Inheriting from Aircraft Hoisting common functionality into a base class

Summary

Files and Resource Management

Files

Binary and text modes The important of encoding Opening a file for writing Writing to files Closing files The file outside of Python Reading files

Readline line by line Reading multiple lines at once

Appending to files File objects as iterators

Context Managers

Managing resources with finally The with-blocks

Moment of zen Binary files

The BMP file format Bitwise operators Writing a BMP file

Reading binary files

File-like objects

You've already seen file-like objects! Using file-like objects

Other resources Summary

Unit testing with the Python standard library

Test cases Fixtures Assertions Unit testing example: text analysis

Running the initial tests Making the test pass

Using fixtures to create temporary files Using the new fixtures Using assertions to test behavior

Counting lines Counting characters

Testing for exceptions Testing for file existence Moment of zen Summary

Debugging with PDB

Debugging commands Palindrome debugging

Bug hunting with PDB Finding infinite loops with sampling Setting explicit breaks Stepping through execution Fixing the bug

Summary

Afterword – Just the Beginning Virtual Environments

Creating a virtual environment Activating a virtual environment Deactivating a virtual environment Other tools for working with virtual environments

Packaging and Distribution

Configuring a package with distutils Installing with distutils Packaging with distutils

Installing Third-Party Packages

Installing pip The Python Package Index

Installing with pip

Installing Local Packages with pip Uninstalling Packages

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