Tuple unpacking
Tue, 19 Nov 2013 |
Python Tutorial |
2 comments
Unpacking a tuple means giving a different name to each element of the tuple. Tuple unpacking is useful because many functions in Python, such as the zip function described in the previous Building lists incrementally section, return tuples. With tuple unpacking, you can easily get at the individual items in these tuples. To unpack a tuple, just assign multiple names on a single line. Put the names you want to unpack into on the left side of the assignment statement and put the tuple on the...
Getting Close Enough with difflib
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People often make mistakes when entering text. The difflib module gives you a way to find strings that are close but not exact matches to a given string gt gt gt right 'The quick brown fox' gt gt gt wrong 'THe quack brown fix' gt gt gt matcher difflib.SequenceMatcher None, right, wrong The ratio method returns a floating point number between 0 and 1 that indicates how close the match is. Higher numbers indicate a closer match. A match higher than 0.6 is usually considered good maybe not by...
Debugging in IDLE
Tue, 09 Aug 2011 |
Python Tutorial
When you run code in IDLE's interactive mode, it informs you of errors the same way you've seen when using interactive mode in a Terminal or shell window. When you run code from the text editor, IDLE also informs you of errors. Depending on the kind of error and on your version of IDLE, the error message appears in a dialog box or in the Python Shell window. You can use the IDLE debugger to step through your program in various ways and display the values of names. The IDLE debugger is shown in...
- A class is like a template
- A colon
- A dot
- A formatting example using string methods
- A tutor
- A twisty maze of codes
- About special package directories
- Absolute imports in Python
- Adding an attribute to an instance
- Adding and changing message headers
- Adding another condition to an if block
- Adding time
- All about class and instance attributes
- All about or
- All about Special Handling
- AlleyOOP Some Object Oriented Programming Concepts
- An instance is a copy made from the template
- An Objects Object Intro to New Style Classes
- Anameis aname except when itsmain
- Applications
- Assigning to a list with slicing
- Assignment always changes
- Asterisk Multiplication
- Augmented assignment doesnt rebind mutable data types
- Avoiding the quirks of default values
- Avoiding unexpected results with integer division
- Being a PUGnosed PIGgie Local User Groups
- Being wordy
- Boolean operators - 2
- Break points
- Briefly meet a few other IDLE commands
- Building a dict out of another dict by using a for loop
- Building lists incrementally
- Builtin functions
- But Wait Theres More The sys Module
- Buy premade bread
- Calling in the Borg Pattern
- Calling the right superclass method
- Cats Cradle Indexing and Slicing
- Changing mutable objects in a shelve database
- Changing the configuration of a logger
- Changing the values of class and instance attributes
- Chapter Accessing the Internet
- Chapter Basic Elements and Syntax
- Chapter Building Applications with Modules and Packages
- Chapter Introducing New Style Classes
- Chapter List - 2 3
- Chapter Processing Lists and Tuples
- Cheese Shop Online Collection of Python Modules
- Choosing between lists and tuples
- Class and Instance Conventions
- Classes
- Classes Just for Data
- Classes modules and functions
- Code block syntax
- Code blocks that create a namespace
- Collecting Globs and Globs of Files
- Combining ingredients
- Combining tests
- Companies that use Python
- Comparatively speaking
- Comparing sequence objects
- Comparison operators - 2
- Compiling regular expressions
- Components of a datetime object
- Converting a sequence
- Create an instance of the Parser class
- Creating a listcomp that applies a filter
- Creating a subclass
- Creating a table
- Creating class methods
- Creating MIME objects via subclasses
- Creating other class attributes
- Cutting through the static about methods
- Data Type Does Matter
- Dealing with duplicate keys
- Dealing with exceptional exceptions
- Decorating Your Code
- Deep copying
- Deleting items from a dict
- Designing for expansion
- Dictionaries
- Difference
- Disappearing lists
- Documenting your program
- Dont use the slots machine
- Effects of changing attribute values
- Element attributes
- Encoding binary data into string data
- End the line of code by typing
- Evaluating a string
- Everything comes from object
- Examining a module
- Examining names
- Example of a custom Text Wrapper object
- Example package structure
- Exceptional Type Testing
- Expression and Comprehension Listcomps and Genexps
- Extracting a value
- False objects
- Fast development
- Files
- Finding information about a URL
- Finding largest and smallest items
- Finding out about dict methods
- Finding out more about string methods
- Finding repeats
- Finding whats in standard modules
- Floating Along
- Focusing on Functions
- For loops
- Formatting date and time information
- Formatting floats
- Formatting with multiple data items in a tuple
- Functional versus methodical
- Functions
- Functions for decoding and encoding character sets
- Functions for reading address headers
- Functions that work with or create lists
- Functions versus methods
- Generator expressions
- Generators yield for faster processing
- Gentlemen and ladies unpack your tuples
- Get in
- Getting field values from a table
- Getting help for messy HTML
- Getting help on a function
- Getting Inside the Factory How Class and Instance Namespaces Interact
- Getting loopy with dicts
- Giving another name to a function
- Gotcha Assigning numbers and strings to slices
- Hings to Know about Control Structures
- Home on the range
- Hooking into the power of special methods
- How a string looks inside Python
- How for works
- How local and global names work with assignment
- How local and global names work with references
- Howdy xranger
- Didnt think they would do that
- Ickling Your Data And Relishing the Outcome
- IDLE automatically indents lines for you
- IDLE Musings
- If statements
- If the information is longer than one screen press the spacebar to see more
- If We May Comment
- If you want to write to the file type a comma and w
- Imagining Complex Numbers
- Immutable or frozen sets
- Import all items from a package
- Importing a module in interactive mode
- Importing a module using a different name
- Importing by name
- Importing items from inside a module
- Include debugging code in your script
- Incorrect logic for Boolean expressions
- Individual modules and packages
- Inheriting from a builtin data type
- Inheriting from multiple superclasses
- Initializing a module
- Initializing the spider
- Input
- Interpolating Between the Lines
- Introducing the call function
- Introduction
- Island of Dr MRO
- It pays to be conventional
- Iterables getcher iterables
- Its easier to ask forgiveness than permission
- Lets continue
- Lets pause for a moment
- List comprehensions
- List indexing and slicing
- List indexing and slicing operations
- Listing the contents of an imported module
- Looping around
- Looping through stringsYou can but why would you want to
- Maintaining Your Programs
- Making a saving throw
- Making Exceptions for Yourself
- Making Names and Storing Values
- Making regexes more readable
- Managing strings
- Manipulating directories and their files
- Mapping it out
- Mary had a little lambda
- Measuring and splitting strings
- Mines bigger than yours Comparing strings
- Mirror mirror on the wall whats the object of this all
- Modular Living Storing Your Code in Files
- Module module where is the module
- Modules
- Most punctuation marks come before digits or letters
- Mutable default values can change
- Namespace searching in classes and superclasses
- Naming names
- Numeric data
- Objects
- Of parsers formatters and writers
- Official documentation
- On the line beneath your class definition header indent four spaces
- On the next line type four spaces and then type the action you want repeated like this
- On the same line in parentheses specify any of the following keyword arguments separated by commas
- On the same line in parentheses type a message as a string
- On the same line type a file or directory pathname and
- On the same line type a space a space and a tuple that includes one data item for each formatting code in the string as shown here
- On the same line type and the items you want to assign
- On the same line type and the new list element so your line looks something like this
- One quote or two
- Open a command window
- Opening a URL
- Opening IDLE
- Operating on sequence objects
- Operators Are Standing By
- Optional but very important On the next lines write the docstring for the function
- Optional modifiers of the formatting code
- Options for the open function
- Order in the dict
- Order please
- Other useful XML modules
- Out of sorts
- Overview - 2 3 4 5 6
- Parameters versus arguments
- Getting Started
- Appendixes
- Pass values or names for any defaultvalue parameters whose default values you want to override
- Passing information to a method
- Pickling restrictions
- Playing the dealer
- Please repeat String operators
- Press the Return or Enter key
- Processing exception arguments
- Processing special characters in a URL
- Programming styles
- Properties of a shelve object
- Pseudocoding your thoughts
- Python and earlier dont support newstyle classes at all and newstyle classes work differently in than in and later
- Python Batteries Included
- Python Programming Codes For Dct And
- Querying the match object
- Quitting interactive mode
- Raising Your Code to New Levels
- Random Access Reference at httpwwwwikipythonorg
- Raw strings
- Reading data from form fields
- Reading email messages
- Reading the spider web
- Recognizing bare naked functions
- Reductionism
- Regex groups
- Relative imports in Python
- Rememberremember to import modules
- Reminds the user to enter a number We discuss how to do this in Chapter Print statements and traceback logs
- Removing indentation from strings
- Representing an email message in Python
- Representing data
- Representing numbers by using the decimal module
- Retrieving items from dicts
- Reversing Your Way to Success
- Roles
- Run the altered script by typing code like this into your browser replace hostnamecgibin with the path to your cgibin directory and replace scriptname with the name of your script
- Run the cgipy module by typing code like this into your browser replacing hostnamecgibin with the path to your cgibin directory
- Running a script from the command line
- Running the spider
- Saving changes to disk
- Seeing a few logging functions
- Seeing environment variables
- Seeing information about a Python object
- Seeing the result of the last expression
- Seeing whats inside Python objects
- Setting up a basic regex search
- Setting up a readandoutput process
- Setting up a SQLite database
- Setting up CGI output in Python
- Setting up the structure
- Shallow copying
- Shell Game Copying and Moving Files
- Similar items
- Simplifying Choices Using Dicts
- Size limits on floats
- Slicing
- Solving OS Incompatibility The os and subprocess Modules
- Sorting a list of strings
- Sorting out module namespaces
- Special characters
- Specifying a function with an arbitrary number of arguments
- Specifying arguments when you call a function
- Stacking and queuing with lists
- Staying in the Loop
- Staying on Time with the datetime and time Modules
- Storing and retrieving values
- Storing pickles on a shelf
- Stringing Them Along
- StringIO special methods
- Strings Disguised as Files
- Subelements
- Subprocessing
- Super strings
- Sussing Out SQL Databases
- Take a breakor else
- Taking your time
- Taming the Wild URL
- TechnicalHash strings or hash browns
- Technicallocation location location
- Technicalordering up some XML
- Technicalother ways of accessing module attributes
- Technicalprogramming to the max
- Technicalstatements and expressions Seeing the difference
- Technicalteaching an old bug new tricks
- Technicalwhat is Unicode and why do we care about it
- Telling the difference between a class object and a function object
- Testing a dict
- Testing the content of strings
- Testing the elements of a sequence object
- Text Wrapper attributes
- Thanks but Ill pass
- That tricky asterisk
- The actions that list objects can do slice append and so on Inheriting overriding and extending
- The big deal about indentation
- The complangpython Newsgroup
- The embedded Python might not include all the standard Python modules
- The function and class definitions
- The function is designed to work in more than one way depending on which arguments are passed
- The inner lives of iterators
- The kind of error
- The Midas touchUnicode versus str
- The most popular list methods
- The Mothership httpwwwpythonorg
- The Python developer community
- The story of Python
- The Three Ds
- The twoloop tango
- The workings of the Spider class
- The Zen of Python
- Think globally act locally
- Tip Additional regex resources
- Tip When not to use a regex
- Tip When not to use inheritance
- To handle each exception a different way use multiple except clauses
- To run the current line of the program and go to the next line type s
- To run the script from the command line type python i followed by the name of the script including the py suffix
- Tools of the re module
- Tracking down tracebacks
- Training your assistant
- Triplescoop
- True and False arent true and false
- Try statements
- Tryexceptelsefinally Together at last
- Trying an OS command with call
- Trying Things
- Tuple packing
- Turning Python into a Calculator with decimal
- Tutorpythonorg and helppythonorg
- Two Ways to Interact with Python
- Type and the value you want to store
- Type the following
- Under One Condition
- Understanding default parameters
- Understanding function namespaces
- Understanding shallow copies
- Understanding Web page errors
- Uniquely Ordered Lists
- Unpacking dictionaries
- Unpacking lists or tuples
- Unraveling Unicode
- Updating a dictionary
- Use append to add an item to the end of the queue
- Use properties
- Use the execute method in a for loop to write the addresses into the database
- Use the function in an expression or in an assignment statement
- Useful calling parameters
- Using a debugger
- Using a default value of None to redefine a mutable object
- Using interactive mode as a calculator
- Using Math Modules
- Using multiple inheritance
- Using Scripts and Modules
- Using the interpolation operator
- Using the range function with a list
- Using tryfinally statements
- Using XML files
- Viewing and changing parameters
- Wandering down the ospath
- Warning Maintaining security when using HTML forms
- Ways to escape
- What a list is
- What a tuple is
- What do you really want
- What sets are and arent
- What spiderpy doesnt have
- Whats new in class methods
- Whats That Idiom
- Whats up
- When it comes to or else
- When you want to check that the program is storing the correct values type p and the name to see its value
- When youre reading a text file
- Where did self go
- Why modularizing is a good idea
- Why Python has two kinds of integers
- Why refactor
- Why to while
- With What Your Bare Hands The Power of with Statements
- Working on a copy of a mutable object
- Working with a Zip File object
- Working with attributes
- Working with builtin functions
- Wrapping text by adding newline characters
- Wrapping text by splitting it up
- Writing a base class for your exceptions
- Writing a basic regex
- Writing a script to work in the Web environment
- Writing and editing code with IDLEs text editor
- Writing multiline programs in interactive mode
- You and who else
- You cant use any of Pythons reserved words or keywords
- You Get All This The builtin Module
- You have had a minimal amount of exposure to programming
- You specify that the name is an attribute of a particular object Discovering where Python looks for names
- Zipfile
- Zipping up a Python library
