Some built-in functions

We do recommend you check out the python doc, see the library reference and click on the built-in functions.

In the previous exercise, Exercise 12 (Functions), we looked into functions and we created a couple of our own. Python comes packaged with some function and these functions are known as the built-in functions.

Some built-in functions

1. abs(x)
2. divmod(a, b)
3. float(x)
4. int(x)
5. input(prompt)
6. len(x)
7. list(x)
8. max(x)
9. min(x)
10. pow(a, b)
11. print(a)
12. range(start, end, step)
13. reversed(x)
14. round(x)
15. sorted(x)
16. str(x)
17. sum(x)
18. type(x)
19. chr(i) and ord(s)

Examples

# abs - returns an absolute value of a number
print(abs(2.34), abs(-23.4))

# round - take a number x, rounds it to y decimal places
print(round(23.23567, 2))

# divmod - Take two args and return their quotient and remainder
print(divmod(23, 6))

# pow - take 2 args and returns x raised to the power y
print(pow(2, 3))

# max, min, sum, sorted, reversed
# the above functions are used on iterables
my_list = [7, 2, 4, 5, 1]

print(f"The largest number is: {max(my_list)}")
print(f"The smallest number is: {min(my_list)}")

print(f"The sum of the numbers is: {sum(my_list)}")

print(f"sorted list: {sorted(my_list)}")

# returns a reversed iterator object - castr to a list
print(f"reversed list: {list(reversed(my_list))}")
# [i for i in reversed(my_list)]

# these function does not alter the object

# chr and ord
# chr - returns a character when a number is passed as arg
print(chr(65))  # this are Unicode related

# ord does the opposite of chr
print(ord('A'))

# float, int, str, list, dict, set
# these converts objects to their types
# type returns the (data) type of an object
# len, range
# we have seen these two before, for the size and also looping

# input, print
# we have also seen them before

Practicals

• Implement a function known as all_f(iterable) . This function returns True if all of the elements of the iterable is True or the iterable is empty, else False. This is the same as the built-in all function.
• Implement a function known as any_f(iterable) . This function returns True if any of the elements of the iterable is True else False. If the iterable is empty, return False.
• Implement the function abs_f(x) which behaves like the abs function, where x , is a number.
• Implement a function, min_max_f that returns the minimum and maximum numbers in a given list passed as an argument. Don't use the built-in function min and max.

Summary

• Built-in functions make working in python much easier and flexible. We don't have to implement our own version of any of those function.
• Built-in functions do not change the object.