Python 2.7 Tutorial Pt 6

In this video I’ll explain how to use functions in Python 2.5 through 2.7. I’m going to cover how to:

• Create Functions
• Pass Values to Functions
• Create Default Values
• Except Unlimited Arguments
• Except Unlimited Key Value Pairs
• Use Recursion
• and more…

Like always, the code follows the video. If you have any questions or comments leave them below. And, if you missed my other Python Tutorials they are available here:

• Python 2.7 Tutorial Pt 1 : Importing Modules and variable types
• Python 2.7 Tutorial Pt 2: Python Lists & Tuples
• Python 2.7 Tutorial Pt 3: The Print Function & Dictionaries
• Python 2.7 Tutorial Pt 4: The IF Statement & Conditional Expression
• Python 2.7 Tutorial Pt 5: Looping with While and For

Here is Some Code that Demonstrates using Python Functions

#! /usr/bin/python

# Define a docstring a special function attribute
globalVariable = 10

def addNumbers(NumOne=1,NumTwo=1):
‘Adds the numbers passed to it’
return NumOne + NumTwo

def addUndefNums(NumOne=1,NumTwo=1,*args):
‘Adds the numbers passed to it’
finalValue = NumOne + NumTwo
if args:
for i in args:
finalValue += i
return finalValue
else:
return finalValue

def scopeFunction():
mainNumber = 10
print id(mainNumber)
print “mainNumber equals”, mainNumber, “in function scopeFunction”
return

def changeGlobal():
globals()['globalVariable'] = 20
return

def createDict(**kvargs):
for i in kvargs:
print i, kvargs[i]
print type(kvargs[i])

print type(kvargs)
print kvargs
return

def factorial(num):
if num == 1:
return 1
else:
return num * factorial(num – 1)

def printNames(first,last):
pass

def main():

# Demonstrate difference between global & local scope
mainNumber = 5
print “mainNumber equals”, mainNumber, “in function main”
scopeFunction()
print “mainNumber equals”, mainNumber, “after scopeFunction”
print id(mainNumber)

# Force a global variable to change
print “globalVariable before changeGlobal =”, globalVariable
changeGlobal()
print “globalVariable after changeGlobal =”, globalVariable

# Create a function with a docstring
print addNumbers(1)
print addNumbers.__doc__

# Add undefined number of numbers with a tuple
print addUndefNums(1,2,3,4,5,6,7,8)

# Create a dictionary
createDict(Name=’Derek’, Age=35, YearBorn=1974)
createDict(Cust1=(‘Derek’,35,1974),Cust2=(‘Sally’,25,1984),Cust3=(‘Paul’,15,1994))

# Demonstrate Recursion
print factorial(3)

“”"
Demonstrate Recursion
def factorial(3):
if 3 == 1:
return 1
else:
return 3 * factorial(2)

def factorial(2):
if 2 == 1:
return 1
else:
return 2 * factorial(1)

def factorial(1):
if 1 == 1:
return 1

“”"

if __name__ == ‘__main__’: main()

9 Responses to “Python 2.7 Tutorial Pt 6”

1. Omar says:

   January 28, 2011 at 5:18 pm

   I just wanted to say that, YOU ARE THE BEST who explains things so freaking good, and simple, and awesomely!
   Since the first tutorial through this one and the others to come, I understood everything so clearly, concise, and fast, You just talk about the main and important stuff we need to learn, you rock! I’m right now at my 3rd year taking Artificial Intelligence which we will use Python, instead of Prolog, and this has been the bestest”, because it’s fast and precisely the topics I need to know/learn.

   Reply
   • admin says:

     January 28, 2011 at 7:10 pm

     Thank you so much. I’m very happy to help in anyway that I can. Nice comments like yours keep me going

     Reply
2. pjordan says:

   July 28, 2011 at 12:18 pm

   these vids are well done, thanks. this may be coming, but i wish you would deal with the issue of calling external modules and procedures.

   thanks also for the code snippets.

   cheers.

   Reply
   • admin says:

     July 28, 2011 at 1:04 pm

     Thanks I’m glad you like them. What do you mean by executing external modules? I cover using external frameworks in future tutorials. Is that what you mean?

     Reply
   • pjordan says:

     July 28, 2011 at 1:36 pm

     from one module–import and call an external module and/or method–in file
     “run.py”, given an second file class_tuorial.py. somethinng like

     import class_tutorial
     from class_tutorial import animal
     reload(animal)

     thanks

     Reply
3. Graham says:

   August 2, 2011 at 6:11 am

   Derek

   You mention a tutorial on regular expressions – which one is that?

   Graham

   Reply
   • admin says:

     August 2, 2011 at 5:49 pm

     I did a couple. Here is part 1 of my regular expression tutorial series using Python Python Regular Expressions

     If you go here and search for regular expressions you’ll see a ton more New Think Tank Sitemap

     Reply
4. Don says:

   April 24, 2012 at 9:29 pm

   Derek:

   Quick Eclipse question.

   I’m attempting to make new practice files in Eclipse but these won’t run even though I’m seemingly in the PyDev. When I go to the menu and click ‘New”> ‘File”, the file it opens won’t run.

   Dumb question, but how do you start new files to run in PyDev (the library is included in the folder I started). I managed to start one practice file that works fine, but I’d obviously like to be able to create many.

   Many thanks.

   Reply
   • admin says:

     April 27, 2012 at 6:45 am

     You have to create your files in the Package Explorer part of Eclipse. Window – Show View – Package Explorer if it isn’t on your screen. Then create a new file by right clicking on the folder named src or default package and then New and then File. I hope that helps. This is a common problem

     Reply