11 Essential Python Functions Every Data Scientist Should Know

1. len()

Returns the number of elements in an object such as lists, tuples, strings, etc.

data = [10, 20, 30, 40]
print(len(data))

4

2. sum()

Returns the sum of elements in an iterable (like lists, arrays).

numbers = [1, 2, 3, 4]
print(sum(numbers))

10

3. type()

Returns the type of a given object, useful for inspecting data types.

x = 3.14
print(type(x))

<class 'float'>

4. map()

Applies a function to all items in an iterable.

numbers = [1, 2, 3, 4]
squared = list(map(lambda x: x**2, numbers))
print(squared)

[1, 4, 9, 16]

5. filter()