Python Mini-Course University of Oklahoma Department of Psychology Day 2 – Lesson 8 Fruitful...
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Python Mini-Course University of Oklahoma Department of Psychology Day 2 – Lesson 8 Fruitful Functions 05/02/09 Python Mini-Course: Day 2 - Lesson 8 1
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Transcript of Python Mini-Course University of Oklahoma Department of Psychology Day 2 – Lesson 8 Fruitful...
Python Mini-CourseUniversity of Oklahoma
Department of Psychology
Day 2 – Lesson 8Fruitful Functions
05/02/09Python Mini-Course: Day 2 - Lesson 81
Lesson objectives
1. Understand how to return values from functions in Python
2. Create “fruitful” functions
05/02/09Python Mini-Course: Day 2 - Lesson 82
The power function revisited
def power(base, exponent): val = base for x in range(1,exponent): val = val * base return val
power(3,4)
05/02/09Python Mini-Course: Day 2 - Lesson 83
The return statement
Syntax return [expression]Exists the enclosing function and returns the value of expression as a result of the call to the function
If expression is omitted, returns None
05/02/09Python Mini-Course: Day 2 - Lesson 84
The return statement
You can only return one valueThat value can be any Python data type (including both built-in and custom data structures)
You can also use the return statement to exit a function early
05/02/09Python Mini-Course: Day 2 - Lesson 85
Exercise
Create a function that computes the distance between any two points when given their coordinates (in 2-D space)
05/02/09Python Mini-Course: Day 2 - Lesson 86
Distance function
def distance(x1, y1, x2, y2):
"""Return the distance between points
(x1, y1) and (x2, y2) as a float"""
return 0.0
05/02/09Python Mini-Course: Day 2 - Lesson 87
Distance function
def distance(x1, y1, x2, y2):
"""Return the distance between points
(x1, y1) and (x2, y2) as a float"""
dx = x2 - x1
dy = y2 - y1
print 'dx is ', dx
print 'dy is ', dy
return 0.0
05/02/09Python Mini-Course: Day 2 - Lesson 88
Distance function
def distance(x1, y1, x2, y2):
"""Return the distance between points
(x1, y1) and (x2, y2) as a float"""
dx, dy = x2 - x1, y2 - y1
result = math.sqrt(dx**2 + dy**2)
return result
05/02/09Python Mini-Course: Day 2 - Lesson 89
Distance function
def distance(x1, y1, x2, y2):
"""Return the distance between points
(x1, y1) and (x2, y2) as a float"""
result = \
math.sqrt((x2-x1)**2 + (y2-y1)**2)
return result
05/02/09Python Mini-Course: Day 2 - Lesson 810
Distance function
def distance(x1, y1, x2, y2):
"""Return the distance between points
(x1, y1) and (x2, y2) as a float"""
return math.sqrt((x2-x1)**2 + (y2-y1)**2)
05/02/09Python Mini-Course: Day 2 - Lesson 811
Creating Boolean functions
Functions that return a Boolean value (True or False) can be used in conditional statements (i.e. if…else…)
05/02/09Python Mini-Course: Day 2 - Lesson 812
is_divisible function
def is_divisible(x, y): if x % y == 0: return True else: return False
is_divisible(16,4)is_divisible(16,3)
05/02/09Python Mini-Course: Day 2 - Lesson 813
is_divisible function
def is_divisible(x, y): return x % y == 0
is_divisible(16,4)is_divisible(16,3)x, y = 16, 5 if is_divisible(x, y): print x,'is divisible by',y
05/02/09Python Mini-Course: Day 2 - Lesson 814
Next session
Iteration methods:RecursionLoops and conditional execution
The for loopThe while loop
Handling strings and text
05/02/09Python Mini-Course: Day 2 - Lesson 815
Suggested exercises
Exercise 5.1 – Fermat's Last TheoremExercise 6.6 – PalindromesExercise 6.7 – is_power functionTurtle exercises from Chaps 4 & 5
05/02/09Python Mini-Course: Day 2 - Lesson 816
