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as alias

Learn to alias with import x as y.

The as alias

The as keyword gives a module a short name (alias). This is used to shorten long module names:

import math as m
print(m.sqrt(16))  # 4.0
print(m.pi)        # 3.14159...

Here the math module is loaded under the name m. Now m.sqrt and m.pi are used. The name math is not available.

This is a common technique to write shorter code.

Common aliases

The Python community has established short names for some modules. These names are used the same way across all projects:

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

These three shortcuts are standard in the data science world. np, pd and plt are recognised by everyone. Inconsistent aliases make code unreadable.

When choosing your own aliases, keep them short but meaningful.

Practice Square root with import math as m

Write import math as m. Then write print(m.sqrt(16)).

Starter code

main.py
# load the math module with alias m
# print the square root via m.sqrt

Sample solution

main.py
import math as m
print(m.sqrt(16))

Expected output

4.0

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Match as aliases

Term Meaning
import math as m math → m
m.sqrt(16) Call with short name
as Alias keyword
math (now gone) Not available

2 After import math as m, what does math.sqrt(16) do?

  • Works
  • Raises NameError Correct answer
  • Does not run but no error
  • Raises ImportError

Explanation: With as m the name math becomes m; math is no longer defined.

3 Complete the as keyword

Question 
import math ____ m
print(m.sqrt(16))
Answer 
import math as m
print(m.sqrt(16))

Explanation: import math as m gives math the alias m.

All lessons in Beginner

1 Python basics

  1. What is Python?
  2. REPL and print
  3. Comments
  4. Indentation blocks
  5. python -c and scripts
  6. Summary - Python basics

2 Variables

  1. Variable assignment
  2. Multiple assignment
  3. Naming variables
  4. id and type
  5. Swapping variables
  6. Summary - Variables

3 Data types

  1. int and float
  2. bool
  3. str basics
  4. None
  5. Type conversion
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add/subtract
  3. Multiply/divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic
  2. Comparison
  3. Logical
  4. Bitwise
  5. Membership and identity
  6. Summary - Operators

6 String basics

  1. f-string
  2. Concatenation
  3. str.format
  4. Raw strings
  5. Triple-quote
  6. Summary - String basics

7 Conditionals

  1. The if statement
  2. elif and else
  3. Nested if
  4. Truthiness
  5. Conditional expression
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. range
  3. The while loop
  4. break and continue
  5. Loop else
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Updating quantity
  5. Putting it together

10 Lists

  1. Declaring lists
  2. Index and slice
  3. List methods
  4. in and count
  5. Sorting lists
  6. Summary - Lists

11 List comprehension

  1. Comprehension basics
  2. Filtered comprehension
  3. Dict and set comprehension
  4. Nested comprehension
  5. Generator expression
  6. Summary - List comprehension

12 Tuple, set and dict

  1. Tuple
  2. Set
  3. Dict basics
  4. Dict methods
  5. Dict comprehension
  6. Summary - Tuple, set and dict

13 Functions

  1. def
  2. return
  3. Docstring
  4. Default parameters
  5. *args and **kwargs
  6. Summary - Functions

14 Function parameters

  1. Positional parameters
  2. Keyword parameters
  3. Keyword-only
  4. Positional-only
  5. Type hints basics
  6. Summary - Function parameters

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string methods

  1. split and join
  2. strip, lstrip, rstrip
  3. replace
  4. find and index
  5. startswith, endswith
  6. Summary - Advanced strings

17 Input and output

  1. input()
  2. int/float conversion
  3. print parameters
  4. f-string formatting
  5. sys.argv
  6. Summary - Input and output

18 Error handling

  1. try/except
  2. else and finally
  3. raise
  4. Exception hierarchy
  5. Custom exceptions
  6. Summary - Error handling

19 Modules

  1. import
  2. from import
  3. as alias
  4. __name__ == '__main__'
  5. Standard library
  6. Summary - Modules

20 Beginner final

  1. Project design
  2. Data model
  3. Business logic
  4. Error handling
  5. Putting it together