Day 2 Lesson 8 Fruitful Functions Python MiniCourse

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Day 2 – Lesson 8 Fruitful Functions Python Mini-Course University of Oklahoma Department of

Day 2 – Lesson 8 Fruitful Functions Python Mini-Course University of Oklahoma Department of Psychology 1 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Lesson objectives 1. Understand how to return values from functions in Python 2. Create

Lesson objectives 1. Understand how to return values from functions in Python 2. Create “fruitful” functions 2 Python Mini-Course: Day 2 - Lesson 8 05/02/09

The power function revisited def power(base, exponent): val = base for x in range(1,

The power function revisited def power(base, exponent): val = base for x in range(1, exponent): val = val * base return val power(3, 4) 3 Python Mini-Course: Day 2 - Lesson 8 05/02/09

The return statement Syntax return [expression] Exists the enclosing function and returns the value

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 4 Python Mini-Course: Day 2 - Lesson 8 05/02/09

The return statement You can only return one value That value can be any

The return statement You can only return one value That 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 5 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Exercise Create a function that computes the distance between any two points when given

Exercise Create a function that computes the distance between any two points when given their coordinates (in 2 -D space) 6 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance between points (x 1, y 1) and (x 2, y 2) as a float""" return 0. 0 7 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance between points (x 1, y 1) and (x 2, y 2) as a float""" dx = x 2 - x 1 dy = y 2 - y 1 print 'dx is ', dx print 'dy is ', dy return 0. 0 8 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance between points (x 1, y 1) and (x 2, y 2) as a float""" dx, dy = x 2 - x 1, y 2 - y 1 result = math. sqrt(dx**2 + dy**2) return result 9 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance between points (x 1, y 1) and (x 2, y 2) as a float""" result = math. sqrt((x 2 -x 1)**2 + (y 2 -y 1)**2) return result 10 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance

Distance function def distance(x 1, y 1, x 2, y 2): """Return the distance between points (x 1, y 1) and (x 2, y 2) as a float""" return math. sqrt((x 2 -x 1)**2 + (y 2 -y 1)**2) 11 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Creating Boolean functions Functions that return a Boolean value (True or False) can be

Creating Boolean functions Functions that return a Boolean value (True or False) can be used in conditional statements (i. e. if…else…) 12 Python Mini-Course: Day 2 - Lesson 8 05/02/09

is_divisible function def is_divisible(x, y): if x % y == 0: return True else:

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) 13 Python Mini-Course: Day 2 - Lesson 8 05/02/09

is_divisible function def is_divisible(x, y): return x % y == 0 is_divisible(16, 4) is_divisible(16,

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 14 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Next session Iteration methods: Recursion Loops and conditional execution The for loop The while

Next session Iteration methods: Recursion Loops and conditional execution The for loop The while loop Handling strings and text 15 Python Mini-Course: Day 2 - Lesson 8 05/02/09

Suggested exercises Exercise 5. 1 – Fermat's Last Theorem Exercise 6. 6 – Palindromes

Suggested exercises Exercise 5. 1 – Fermat's Last Theorem Exercise 6. 6 – Palindromes Exercise 6. 7 – is_power function Turtle exercises from Chaps 4 & 5 16 Python Mini-Course: Day 2 - Lesson 8 05/02/09