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Python Programming 101
Functions
Functions allow us to reuse bits of code. For example, say that we are calculating tax on transactions. We can wrap up our code in a functional unit and give it a name:
def calculate_tax(price, tax):
sales_tax = price * tax
total = price + sales_ tax
return total
From then on we can just call that name and pass it some information (called parameters):
calculate_tax(53.79, 0.075)
This will save us time as well as make our code easier to review. Lets take a look at some more in-depth learning resources.
Learning Resources
- Chapter 4 - Functions (Slides, Printable Slides, Streaming Video, Download Video, Lecture Audio)
- Worked Exercise Screencasts: 4.4 (suggest download)
Dive Into Python3: Declaring Functions
Practice
Post chapter excercises and questions below.
Q: What is an example of a machine or process that takes external input and returns a modified output?
Q: How many tasks do you think that an individual function should generally perform?
Comments
Q: What is an example of a
Q: What is an example of a machine or process that takes external input and returns a modified output?
A function, takes external inputs and returns a modified output.
Q: How many tasks do you think that an individual function should generally perform?
An individual function should perform a single task.
Alfonso
Q: What is an example of a
Q: What is an example of a machine or process that takes external input and returns a modified output?
printer
fax machine
Q: How many tasks do you think that an individual function should generally perform?
function only perform single tasks but a function can be used multiple times.
ex 4.4
#working with functions()
def computepay(time, rate):
if time > 40:
over = (int(hours) - 40) * 1.5
time = 40 + float(over)
pay = float(time) * float(rate)
print pay
hours = raw_input("Enter hours worked:")
try:
hours = int(hours)
except:
print 'error, enter a number\n'
rate = raw_input("Enter rate at which worked:")
try:
rate = int(rate)
except:
print 'error, enter a number\n'
computepay(hours, rate)
ex 4.5
#Student Grade
score = raw_input('Enter student score(0.0-1.0): ')
try:
score = float(score)
if score < 0.6:
print 'F'
elif score <= 0.69:
print 'D'
elif score <= 0.79:
print 'C'
elif score <= 0.89:
print 'B'
elif score <= 1.0:
print 'A'
else:
print 'Bad Score'
except:
print 'error Bad Score'
Q: What is an example of a
Q: What is an example of a machine or process that takes external input and returns a modified output?
A human being: eats input and, erm, creates modified output
Q: How many tasks do you think that an individual function should generally perform?
Any number internal to the function, but one result.
chapter 4 exercises:
https://github.com/brotherhutch/python101/tree/master/chapter4
Q: What is an example of a
Q: What is an example of a machine or process that takes external input and returns a modified output?
Function(input): Go-to-Gym(keen but un-fit Gym Member)
Process: Excercise Gym-Member almost to failure
Output: Slightly Fitter Gym-Member
Q: How many tasks do you think that an individual function should generally perform?
In general one per individual function. But a Function may have any number of related Functions within it, each performing a single related task. Very important that the function only deals with closely related tasks.
Chapter 4 Exercises:
Chapter 4 Exercises: https://github.com/jwmnatl/jwmnatl.github.com/blob/master/python101/chap...
Q: What is an example of a machine or process that takes external input and returns a modified output?
A: I'll go 18th century and say the cotton gin. Input cotton, returns fibers
Q: How many tasks do you think that an individual function should generally perform?
A: Can perform several tasks within the function but just one task can result in output. So generally speaking, one.
Q: What is an example of a
Q: What is an example of a machine or process that takes external input and returns a modified output?
TV remote control
Q: How many tasks do you think that an individual function should generally perform?
One.
Exercises chapter 4: http://www.pastie.org/2021666