Built-in Functions

We will be discussing some useful built-in functions in this unit. For example, int,bool,float,dict, etc are all built-in functions.

`len()`, `min()`, `max()`, `zip()` functions

len(): This function returns the length of a String, Dictionary, List, Tuple or Set.
min(): This function returns the minimum possible item from a List.
max(): This function returns the maximum possible item from a List.
zip(): This function zips multiple Lists together, returning a set of Tuples.

Let's see an example:

listExample1 = ['a', 'b', 'c']
listExample2 = [1, 2, 3]
print(zip(listExample1, listExample2))

This would output:

[('a', 1), ('b', 2), ('c', 3)]

For the other functions, practice them using random examples. This will help in practicing better.

`map()` function

This function helps us in applying a condition or expression to the entire List, avoiding the use of a messy Loop.

For example, if we want to make a new list with just odd numbers, we would usually use a Loop.

list = range(1,11)
newList = []
for i in list:
    if i % 2 != 0:
        newList.append(i)

print(newList)

This would output:

[1, 3, 5, 7, 9]

Now, with map(), we can do this:

objects = range(1,11)
newObjects = list(map(lambda x: x % 2 != 0, objects ))

This will also output:

[1, 3, 5, 7, 9]

`filter()` function

This function filters a List. For example, if you have a List of numbers from 1 to 10, and wish to have a new List with the odd numbers, you can use this function.

list = range(1,11)
newList = filter(lambda x: x % 2 != 0, list)
print(newList)

This would output:

[1, 3, 5, 7, 9]

`any()` function

This function checks a list of Boolean variables, and returns True if any one of them is True. This is the same as the OR function, where even one True returns a True for the entire condition.

list = range(1,10)
if any(map(lambda x:x % 2 == 0, list)):
    print("List has even numbers!")

As you can guess, the output is:

List has even numbers!

`all()` function

Similar to above, this function serves as the AND function. In other words, only if all the Boolean variables are True, it will output True.

list = range(1,10)
if all(map(lambda x:x % 2 == 0, list)):
    print("List has all even numbers!")
else:
    print('Failed')

This outputs:

Failed

This is because the list has multiple numbers.

Built-in Functions