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Lecture # 27
Python I
Python
• “Interpretive” language (vs. compiled)So is HTML, JavaScript.
• Python supports file I/O. JavaScript doesn’t
• Python is a serious web programming language used by Google, ILM, etc.
Jython
• Jython is a “dialect” of Python
• Python is implemented in CJython is implemented in Java
• We use JES JES = Jython Environment for Students
Downloading Jython
• http://code.google.com/p/mediacomp-jes/
• http://code.google.com/p/mediacomp-jes/downloads/list
Using Jython
• Select JES from “Programs”
• Click on the black part of the UI after the command prompt >>>
Jython DEMO
• print 5 + 9• print “Hello”• x = 5 + 9• print x• message = “Hello There”• print message
Jython DEMO
• print 5 + 9• print “Hello”• x = 5 + 9• print x• message = “Hello There”• print message
• Note: Python is case sensitive.“Print” and “Message” won’t work.
Jython DEMO Pictures• pickAFile()
Jython DEMO Pictures• pickAFile()
• print pickAFile()
Jython DEMO Pictures• pickAFile()
• print pickAFile()
• file = pickAFile()
Jython DEMO Pictures• pickAFile()
• print pickAFile()
• file = pickAFile()
• print file
Jython DEMO Pictures• pickAFile()
• print pickAFile()
• file = pickAFile()
• print file
• pict=makePicture(file) # interpret as picture
Jython DEMO Pictures• pickAFile()
• print pickAFile()
• file = pickAFile()
• print file
• pict=makePicture(file) # interpret as picture
• show(pict) # display as picture
How could we do this all at once?
How could we do this all at once?
show(makePicture(pickAFile()))
How could we do this all at once?
show(makePicture(pickAFile()))
Now lets save it as a Python Program:displayPict.py
How could we do this all at once?
show(makePicture(pickAFile()))
Now lets save it as a Python Program:displayPict.py
And run it:open itand load it
How could we do this all at once?
show(makePicture(pickAFile()))
Now lets save it as a Python Program:displayPict.py
And run it:open itand load it King of the “1-liners”
Jython DEMO Sound• file = pickAFile()
• print file
• sound=makeSound(file) # interpret as sound
• play(sound) # lets listen to it
All together: play(makeSound(pickAFile()))
• Save as a Python program and run it
Jython Functions
def myFunction(): colon
Jython Functions
def myFunction(): colon
parentheses
Jython Functions
def myFunction(): colon
parentheses function name
Jython Functions
def myFunction(): colon
parentheses function name
“def” instead of “function()”
Jython Functions
def myFunction(): colon
parentheses function name
“def” instead of “function()”
The function must be called somewhere
Jython Functions
def myFunction():
block of commands
Jython Functions
def myFunction():
block of commands
Note indentation!
Jython Functions: Indentation
• Indentation is critical in Python
• Indentation associates these commands with this function
• Indentation separates commands from other functions
Jython Function: Example
def pickAndShow():file = pickAFile()myPict = makePicture(file)show(myPict)
pickAndShow() # somewhere we have to call the function