- •Introduction
- •Introduction - What, Why, Who etc.
- •Why am I writing this?
- •What will I cover
- •Who should read it?
- •Why Python?
- •Other resources
- •Concepts
- •What do I need?
- •Generally
- •Python
- •QBASIC
- •What is Programming?
- •Back to BASICs
- •Let me say that again
- •A little history
- •The common features of all programs
- •Let's clear up some terminology
- •The structure of a program
- •Batch programs
- •Event driven programs
- •Getting Started
- •A word about error messages
- •The Basics
- •Simple Sequences
- •>>> print 'Hello there!'
- •>>>print 6 + 5
- •>>>print 'The total is: ', 23+45
- •>>>import sys
- •>>>sys.exit()
- •Using Tcl
- •And BASIC too...
- •The Raw Materials
- •Introduction
- •Data
- •Variables
- •Primitive Data Types
- •Character Strings
- •String Operators
- •String operators
- •BASIC String Variables
- •Tcl Strings
- •Integers
- •Arithmetic Operators
- •Arithmetic and Bitwise Operators
- •BASIC Integers
- •Tcl Numbers
- •Real Numbers
- •Complex or Imaginary Numbers
- •Boolean Values - True and False
- •Boolean (or Logical) Operators
- •Collections
- •Python Collections
- •List
- •List operations
- •Tcl Lists
- •Tuple
- •Dictionary or Hash
- •Other Collection Types
- •Array or Vector
- •Stack
- •Queue
- •Files
- •Dates and Times
- •Complex/User Defined
- •Accessing Complex Types
- •User Defined Operators
- •Python Specific Operators
- •More information on the Address example
- •More Sequences and Other Things
- •The joy of being IDLE
- •A quick comment
- •Sequences using variables
- •Order matters
- •A Multiplication Table
- •Looping - Or the art of repeating oneself!
- •FOR Loops
- •Here's the same loop in BASIC:
- •WHILE Loops
- •More Flexible Loops
- •Looping the loop
- •Other loops
- •Coding Style
- •Comments
- •Version history information
- •Commenting out redundant code
- •Documentation strings
- •Indentation
- •Variable Names
- •Modular Programming
- •Conversing with the user
- •>>> print raw_input("Type something: ")
- •BASIC INPUT
- •Reading input in Tcl
- •A word about stdin and stdout
- •Command Line Parameters
- •Tcl's Command line
- •And BASIC
- •Decisions, Decisions
- •The if statement
- •Boolean Expressions
- •Tcl branches
- •Case statements
- •Modular Programming
- •What's a Module?
- •Using Functions
- •BASIC: MID$(str$,n,m)
- •BASIC: ENVIRON$(str$)
- •Tcl: llength L
- •Python: pow(x,y)
- •Python: dir(m)
- •Using Modules
- •Other modules and what they contain
- •Tcl Functions
- •A Word of Caution
- •Creating our own modules
- •Python Modules
- •Modules in BASIC and Tcl
- •Handling Files and Text
- •Files - Input and Output
- •Counting Words
- •BASIC and Tcl
- •BASIC Version
- •Tcl Version
- •Handling Errors
- •The Traditional Way
- •The Exceptional Way
- •Generating Errors
- •Tcl's Error Mechanism
- •BASIC Error Handling
- •Advanced Topics
- •Recursion
- •Note: This is a fairly advanced topic and for most applications you don't need to know anything about it. Occasionally, it is so useful that it is invaluable, so I present it here for your study. Just don't panic if it doesn't make sense stright away.
- •What is it?
- •Recursing over lists
- •Object Oriented Programming
- •What is it?
- •Data and Function - together
- •Defining Classes
- •Using Classes
- •Same thing, Different thing
- •Inheritance
- •The BankAccount class
- •The InterestAccount class
- •The ChargingAccount class
- •Testing our system
- •Namespaces
- •Introduction
- •Python's approach
- •And BASIC too
- •Event Driven Programming
- •Simulating an Event Loop
- •A GUI program
- •GUI Programming with Tkinter
- •GUI principles
- •A Tour of Some Common Widgets
- •>>> F = Frame(top)
- •>>>F.pack()
- •>>>lHello = Label(F, text="Hello world")
- •>>>lHello.pack()
- •>>> lHello.configure(text="Goodbye")
- •>>> lHello['text'] = "Hello again"
- •>>> F.master.title("Hello")
- •>>> bQuit = Button(F, text="Quit", command=F.quit)
- •>>>bQuit.pack()
- •>>>top.mainloop()
- •Exploring Layout
- •Controlling Appearance using Frames and the Packer
- •Adding more widgets
- •Binding events - from widgets to code
- •A Short Message
- •The Tcl view
- •Wrapping Applications as Objects
- •An alternative - wxPython
- •Functional Programming
- •What is Functional Programming?
- •How does Python do it?
- •map(aFunction, aSequence)
- •filter(aFunction, aSequence)
- •reduce(aFunction, aSequence)
- •lambda
- •Other constructs
- •Short Circuit evaluation
- •Conclusions
- •Other resources
- •Conclusions
- •A Case Study
- •Counting lines, words and characters
- •Counting sentences instead of lines
- •Turning it into a module
- •getCharGroups()
- •getPunctuation()
- •The final grammar module
- •Classes and objects
- •Text Document
- •HTML Document
- •Adding a GUI
- •Refactoring the Document Class
- •Designing a GUI
- •References
- •Books to read
- •Python
- •BASIC
- •General Programming
- •Object Oriented Programming
- •Other books worth reading are:
- •Web sites to visit
- •Languages
- •Python
- •BASIC
- •Other languages of interest
- •Programming in General
- •Object Oriented Programming
- •Projects to try
- •Topics for further study
Complex or Imaginary Numbers
If you have a scientific or mathematical background you may be wondering about complex numbers? If you aren't you may not even have heard of complex numbers! Anyhow some programming languages, includinh Python, provide builtin support for the complex type while others provide a library of functions which can operate on complex numbers. And before you ask, the same applies to matrices too.
In Python a complex number is represented as:
(real+imaginaryj)
Thus a simple complex number addition looks like:
>>>M = (2+4j)
>>>N = (7+6j)
>>>print M + N (9+10j)
All of the integer operations also apply to complex numbers.
Boolean Values - True and False
Like the heading says, this type has only 2 values - either true or false. Some languages support boolean values directly, others use a convention whereby some numeric value (often 0) represents false and another (often 1 or -1) represents true.
Boolean values are sometimes known as "truth values" because they are used to test whether something is true or not. For example if you write a program to backup all the files in a directory you might backup each file then ask the operating system for the name of the next file. If there are no more files to save it will return an empty string. You can then test to see if the name is an empty string and store the result as a boolean value (true if it is empty). You'll see how we would use that result later on in the course.
Boolean (or Logical) Operators
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Effect |
Example |
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A and B |
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AND |
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True if A,B are both True, False otherwise. |
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A or B |
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OR |
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True if either or both of A,B are true. False if both A |
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and B are false |
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A == B |
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Equality |
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True if A is equal to B |
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A != B |
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Inequality |
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True if A is NOT equal to B. |
or |
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A <> B |
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not B |
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Negation |
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True if B is not True |
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Note: the last one operates on a single value, the others all compare two values.
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