python programming
DESCRIPTION
Python programming. Introduction to the JES environment and basics of Python. Python. The programming language we will be using is called Python http://www.python.org It’s used by companies like Google, Industrial Light & Magic, Nextel, and others - PowerPoint PPT PresentationTRANSCRIPT
Python programming
Introduction to the JES environment and basics of Python
Python
• The programming language we will be using is called Python– http://www.python.org– It’s used by companies like Google, Industrial Light &
Magic, Nextel, and others• The kind of Python we’re using is called Jython
(Java-based Python)– http://www.jython.org
• We’ll be using a specific tool to make Python programming easier, called JES (Jython Environment for Students).– http://coweb.cc.gatech.edu/mediaComp-teach/26
JES - Jython Environment for Students
Program Area
Command Area
Program area- A simple editor for programs
Command area- Interaction with Jython
>>> 5 + 38>>> ‘spam’‘spam’>>> “spam”‘spam’>>> “spam and more spam”‘spam and more spam’>>> ‘spam’ + ‘spam’‘spamspam’
Python interaction through commands
Anything you type in command area is evaluated and its value is displayed
• Example:
prompt
>>> print 5 + 38>>> print ‘spam’spam>>> ‘spam’ + ‘spam’‘spamspam’>>> print ‘spam’ + ‘spam’Spamspam
print displays the value of an expression
• In many cases it makes no difference whether you use print - the result gets displayed anyway.
Note: no quotes!
Command Area Editing
• Up/down arrows walk through command history
• You can edit the line at the bottom– Just put the cursor at the end of the line
before hitting Return/Enter.
Variables are names for data
Example:
a= 3
b= -1
c = 2
x = 0
f = a*x*x + b*x + c
Variables -more examples
• Variables of other typesnewsItem = “You’ve got spam!”
• Variables keep their value for the duration of a program or until they get a new value through a new assignment
a = 3
b = a *2 + 5
a = 0
Up to this point the value of a is still 3, but then it changes to 0
Types of data
• Integernum = -3
• Floating point numberanswer = 62.49
• Characterletter = ‘5’
• Stringnote = “lol jkjk”
Python functions
• Python has a lot of built-in functions for general mathematical manipulation, eg:
• sqrt(4) - computes the square root of 4• ord(‘A’) - computes the ASCII code for
character ‘A’ (i.e., a numeric code)• str(4) – produces a string corresponding to
a numberExample: print (-b+sqrt(b*b - 4*a*c))/2*a
Special JES-Python functions
• JES defines some special functions for media computation
Functions in general
F(a,b)
4
‘a’ F(4, ‘a’)
side-effects
Example: sqrt()
sqrt(a)4 2
side-effects
Example: showInformation()
showInformation(message)message
Pops up a new window displaying the message text
showInformation(message):message: the message to show to the userOpens a message dialog to the user showing information
Exploring more functions
• The JES Functions menu has functions arranged by type - check them out!
• Can you find a function that inputs a number?
• Can you find under what category pickAFile() is listed?
Reading
• Chapters 1, and Sections 2.1-2.4 from “Introduction to Computing and Programming in Python” (up to page 22)