Python from keyword

The from keyword in Python is used to import specific parts of a module. It allows you to bring only the needed functionalities into your code, improving readability and efficiency. It’s typically paired with the import keyword.

Syntax

from module_name import specific_item

• module_name: The name of the module you want to import from.
• specific_item: The specific class, function, or variable to import from the module.

You can also use the * wildcard to import all items from a module:

from module_name import *

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Why Use from?

1. Selective Imports: Only import what you need to reduce memory usage and avoid polluting the namespace.
2. Simplified Access: Access imported items directly without prefixing them with the module name.
3. Improves Readability: Makes the code cleaner and more readable by importing specific items.

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Common Scenarios

1. Importing a Specific Function

from math import sqrt

# Use the imported sqrt function

result = sqrt(16)

print(result)

Output:

4.0

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2. Importing Multiple Items

from math import sqrt, pow

# Use the imported sqrt and pow functions

result1 = sqrt(25)

result2 = pow(2, 3)

print(result1, result2)

Output:

5.0 8.0

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3. Importing All Items

from math import *

# Use various math functions without prefixing with math

result = sin(pi / 2)

print(result)

Output:

1.0

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4. Renaming Imports

You can rename an imported item using the as keyword for clarity or to avoid naming conflicts.

from math import sqrt as square_root

# Use the renamed function

result = square_root(9)

print(result)

Output:

3.0

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5. Importing from Custom Modules

If you have a custom Python file (module), you can import specific items from it.

File: my_module.py

def greet(name):

    return f"Hello, {name}!"

Main Script:

from my_module import greet

# Use the imported greet function

print(greet("Alice"))

Output:

Hello, Alice!

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6. Handling Name Conflicts

If a function or variable in the module conflicts with a name in your code, use from with as to resolve the issue.

from math import pi as math_pi

pi = 3.14  # Local variable

print(f"Local pi: {pi}, Math module pi: {math_pi}")

Output:

Local pi: 3.14, Math module pi: 3.141592653589793

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Common Scenarios

Selective Imports: Importing only what’s necessary avoids unnecessary overhead.

from datetime import datetime

print(datetime.now())

Output:

Current date and time.

Cleaner Code: Avoids prefixing module names.

from random import randint

print(randint(1, 10))

Output:

A random integer between 1 and 10.

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Key Notes

1. Avoid from module import * in Large Codebases: Using * imports all items from a module, which can lead to namespace pollution and unexpected conflicts.
2. Use as for Clarity: Rename imported items to improve readability or resolve naming conflicts.
3. Combine with Standard Imports: Use from imports alongside regular imports for modularity.

By mastering the from keyword, you can write more modular, efficient, and readable Python code!