Python

What does “__init__” do in Python?

The __init__ function is a constructor in Python.  The __init__.py file makes Python treat the containing folder as a Python package.

What does dynamically typed language mean in Python?

A dynamically typed language is a language where there is no need to declare a variable type on an assignment. Python is a dynamically typed language which means that for example, x = 0 does not need a type declaration because the Python interpreter automatically assumes x is an integer.

What does the “with” keyword do in Python?

The with keyword is a statement used to make exception handling cleaner and simpler.

# using with statement
with open('myfile.txt', 'w') as file:
    file.write('DataCamp Black Friday Sale!!!')

The above handles try, finally, and close on a single statement.

What is “list comprehension” in Python and what does it do?

List comprehension offers a shorter syntax to create a list based on the values of an existing list. For example:

fruits = ["apple", "banana", "cherry", "kiwi", "mango"]
newlist = []

for x in fruits:
  if "a" in x:
    newlist.append(x)

print(newlist)

This can be achieved using list comprehension using the following syntax:

fruits = ["apple", "banana", "cherry", "kiwi", "mango"]

newlist = [x for x in fruits if "a" in x]

print(newlist)

What is the “map” function in Python and what does it do?

The map function returns an iterator after applying a function to an iterable object.

# Return double of n
def addition(n):
    return n + n

# We double all numbers using map()
numbers = (1, 2, 3, 4)
result = map(addition, numbers)

What does the “get” function do on a Python dictionary?

The get function in Python returns a value from the list by key name, optionally allowing for a default value to be returned if the key does not exist.

dictionary.get(keyname, value)