Python PCEP Creating Simple Functions
- 1. Creating simple functions Module 3 Functions, Tuples, Dictionaries, Data processing
- 2. Module 3 Creating simple functions Evaluating the BMI def bmi(weight, height): return weight / height ** 2 print(bmi(52.5, 1.65)) def ft_and_inch_to_m(ft, inch = 0.0): return ft * 0.3048 + inch * 0.0254 def lb_to_kg(lb): return lb * 0.45359237 def bmi(weight, height): if height < 1.0 or height > 2.5 or weight < 20 or weight > 200: return None return weight / height ** 2 print(bmi(weight = lb_to_kg(176), height = ft_and_inch_to_m(5, 7)))
- 3. Module 3 Creating simple functions Check triangles 1 def is_a_triangle(a, b, c): if a + b <= c or b + c <= a or c + a <= b: return False return True print(is_a_triangle(1, 1, 1)) print(is_a_triangle(1, 1, 3)) def is_a_triangle(a, b, c): return a + b > c and b + c > a and c + a > b print(is_a_triangle(1, 1, 1)) print(is_a_triangle(1, 1, 3)) True False True False
- 4. Module 3 Creating simple functions Check triangles 2 def is_a_triangle(a, b, c): return a + b > c and b + c > a and c + a > b a = float(input('Enter the first side's length: ')) b = float(input('Enter the second side's length: ')) c = float(input('Enter the third side's length: ')) if is_a_triangle(a, b, c): print('Yes, it can be a triangle.') else: print('No, it can't be a triangle.')
- 5. Module 3 Creating simple functions Check right-angle triangle def is_a_triangle(a, b, c): return a + b > c and b + c > a and c + a > b def is_a_right_triangle(a, b, c): if not is_a_triangle(a, b, c): return False if c > a and c > b: return c ** 2 == a ** 2 + b ** 2 if a > b and a > c: return a ** 2 == b ** 2 + c ** 2 print(is_a_right_triangle(5, 3, 4)) print(is_a_right_triangle(1, 3, 4))
- 6. Module 3 Creating simple functions Evaluate a triangle's area Heron's formula: def is_a_triangle(a, b, c): return a + b > c and b + c > a and c + a > b def heron(a, b, c): p = (a + b + c) / 2 return (p * (p - a) * (p - b) * (p - c)) ** 0.5 def area_of_triangle(a, b, c): if not is_a_triangle(a, b, c): return None return heron(a, b, c) print(area_of_triangle(1., 1., 2. ** .5))
- 7. Module 3 Creating simple functions Factorials 0! = 1 (yes! it's true) 1! = 1 2! = 1 * 2 3! = 1 * 2 * 3 4! = 1 * 2 * 3 * 4 : : n! = 1 * 2 ** 3 * 4 * ... * n-1 * n def factorial_function(n): if n < 0: return None if n < 2: return 1 product = 1 for i in range(2, n + 1): product *= i return product for n in range(1, 6): # testing print(n, factorial_function(n)) 1 1 2 2 3 6 4 24 5 120
- 8. Module 3 Creating simple functions Fibonacci numbers • the first element of the sequence is equal to one (Fib1 = 1) • the second is also equal to one (Fib2 = 1) • every subsequent number is the the_sum of the two preceding numbers: (Fibi = Fibi-1 + Fibi-2) fib_1 = 1 fib_2 = 1 fib_3 = 1 + 1 = 2 fib_4 = 1 + 2 = 3 fib_5 = 2 + 3 = 5 fib_6 = 3 + 5 = 8 fib_7 = 5 + 8 = 13 def fib(n): if n < 1: return None if n < 3: return 1 elem_1 = elem_2 = 1 the_sum = 0 for i in range(3, n + 1): the_sum = elem_1 + elem_2 elem_1, elem_2 = elem_2, the_sum return the_sum for n in range(1, 10): # testing print(n, "->", fib(n)) 1 -> 1 2 -> 1 3 -> 2 4 -> 3 5 -> 5 6 -> 8 7 -> 13 8 -> 21 9 -> 34
- 9. Module 3 Creating simple functions Recursion Fibi = Fibi-1 + Fibi-2 def fib(n): if n < 1: return None if n < 3: return 1 return fib(n - 1) + fib(n - 2) n! = (n-1)! × n def factorial_function(n): if n < 0: return None if n < 2: return 1 return n * factorial_function(n - 1)
- 10. Module 3 Creating simple functions Key takeaways A function can call other functions or even itself. When a function calls itself, this situation is known as recursion. Recursive calls consume a lot of memory. # Recursive implementation of the factorial function. def factorial(n): if n == 1: # The base case (termination condition.) return 1 else: return n * factorial(n - 1) print(factorial(4)) # 4 * 3 * 2 * 1 = 24