Author: 👤 David Beazley & 👤 Brian K. Jones

Type: #book

Genres: #comp-sci

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Python Cookbook

Recipes for Mastering Python 3

1 Data Structures and Algorithms

• Using deque to keep fixed-length arrays of the previous N items
• Using heapq.nsmallest to find the smallest or largest N items
• Using defaultdict to map keys to multiple values
• Calculating and sorting with dictionary data
• Set operations can be used on dictionary .keys() and .items() calls
• Removing duplicates from a sequence while maintaining order
• Using slice objects to name slices and avoid hardcoding
• Using collections.Counter to find most common items
• collections.Counter features
• Sorting objects by a particular attribute
• Grouping objects together based on a field with itertools.groupby()
• Using generator expressions as arguments for reduction functions

2 Strings and Text

• Using re.split() for advanced string splitting
• Checking the start or end of a string with .startswith() and .endswith()
• Replacing text with re.sub()

3 Numbers, Dates and Times

• Rounding to tens, hundreds and thousands
• Lists vs Numpy arrays
• Prefer numpy universal native functions over looping
• Numpy multidimensional arrays
• Numpy matrices vs arrays
• Converting timedelta objects to total seconds
• Creating a range() function equivalent for dates
• Storing dates internally

4 Iterators and Generators

• Iterating through a custom object
• Iterating in reverse over a sequence
• Looping through items in separate containers
• Flattening a nested sequence

5 Files and I/O

• Printing to a file
• Changing the print function separator character
• Prevent accidentally overwriting files
• Manipulating path names with os.path
• Testing for the existence of files or directories with os.path
• List all files and directories

6 Data Encoding and Processing

• Reading CSV data
• Writing CSV data
• Reading and writing JSON data

7 Functions

• What is a closure?

8 Classes and Objects

• Setting the __repr__ method
• Setting the __str__ method
• Saving memory while using large numbers of instances
• Using _internal attributes and methods
• Using __private attributes and methods
• Using the @property decorator
• Using super() to call parent methods
• Defining more than one constructor in a class
• What is a mixin?
• Extending classes with mixins
• Calling methods with string names
• Using operator.methodcaller()
• Making classes support comparison operators

10 Modules and Packages

• Using relative imports
• Splitting a module into separate files

13 Utility Scripting and System Administration

• Prompting for user password at runtime
• Creating and unpacking archive files
• Launching a web browser

14 Testing, Debugging and Exceptions

• Conditionally skipping unit tests
• Handling multiple exceptions
• Creating custom exceptions
• Timing a function call with timetit()
• Timing a function with a decorator
• Profiling module runtime

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