Python Lambda Functions

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Questions and Answers

What does a function define in programming?

A collection of data types used in a program

A constant value that cannot change

A block of code that runs only when defined

An independent code space that executes when called (correct)

How does a function receive data?

By direct assignment of values

By modifying global variables

Through its return statement only

Via input parameters passed into it (correct)

Which statement is true regarding local and global variables?

Local variables are accessible solely within their function (correct)

Local variables can be accessed outside their function only

Global variables are exclusively accessible within functions

Global variables cannot be modified within functions

What is the function of nonlocal variables?

To allow access to variables in the outer function scope Signup and view all the answers

What does a function call represent in programming?

A reference made to the function's address space Signup and view all the answers

Which of the following improves code usability for future developers?

Including a README file Signup and view all the answers

What should be included in the setup.py file?

Project dependencies Signup and view all the answers

What is one benefit of having proper comments in code?

It enhances readability and usability Signup and view all the answers

Which naming convention is recommended for Python class names?

CamelCase Signup and view all the answers

What type of comment is suitable for describing a multi-line function?

Triple quotes comment Signup and view all the answers

What kind of names should be avoided for variables in Python?

Single-letter names Signup and view all the answers

Why is properly separating long variable names with underscores advised?

To improve code readability Signup and view all the answers

Which of the following is NOT recommended for variable naming?

Abbreviating words excessively Signup and view all the answers

What is a standard practice for writing a Python module?

Each module includes a file named init.py Signup and view all the answers

Which package is best suited for working with tabular or time-series data?

Pandas Signup and view all the answers

What is the primary function of the Requests package in Python?

Making HTTP requests Signup and view all the answers

Which package provides a high-level interface for creating statistical graphics?

Seaborn Signup and view all the answers

What kind of tasks is the Pytest package used for?

Testing application code and libraries Signup and view all the answers

Which package is an important HTTP client used for generating requests in Python?

Urllib3 Signup and view all the answers

In the example provided, what will be the output of print(calc.add(10, 2)) if calc.py contains an add function?

12 Signup and view all the answers

What type of data does the Pillow package primarily process?

Image data Signup and view all the answers

What does a lambda function return when assigned to an identifier?

A function object Signup and view all the answers

What is a higher-order function?

A function that takes other functions as arguments Signup and view all the answers

How does the filter() function work in Python?

It only returns items that evaluate as True with the provided function Signup and view all the answers

What is one primary way that docstrings differ from comments in Python?

Docstrings can be accessed via the doc attribute. Signup and view all the answers

What will the following code output: `new_list = list(map(lambda x: x * 2, [1, 5, 4, 6, 8, 11, 3, 12]))`?

[2, 10, 8, 12, 16, 22, 6, 24] Signup and view all the answers

Which of the following describes the output of the filter() function?

Only items that are even numbers Signup and view all the answers

Which of the following is a correct format for a single-line docstring?

'''This is a docstring.''' Signup and view all the answers

What is the primary purpose of the map() function in Python?

To apply a function to all items in a list and return a new list Signup and view all the answers

What does the print function's docstring indicate about the 'sep' argument?

It specifies the string inserted between values, defaulting to a space. Signup and view all the answers

Which of the following statements is true regarding lambda functions?

They can be used as arguments to higher-order functions Signup and view all the answers

What should be avoided in a well-structured single-line docstring?

Including descriptive details about the function. Signup and view all the answers

Which of the following will return a list of even numbers from my_list using filter()?

new_list = list(filter(lambda x: x % 2 == 0, my_list)) Signup and view all the answers

What is indicated by the doc attribute in a function like square(n)?

It provides a description of the function's purpose. Signup and view all the answers

Which of the following options correctly exemplifies a modular structure in programming?

Categorizing functions into input, output, and processing modules. Signup and view all the answers

What is an essential characteristic of a well-structured code in terms of programming paradigms?

It utilizes structured programming principles. Signup and view all the answers

What does the output of the command 'print(square.doc)' illustrate?

It displays the string literal provided in the square function's docstring. Signup and view all the answers

Study Notes

Lambda Functions and Higher-Order Functions

Lambda functions in Python are anonymous functions defined with the lambda keyword.
Commonly used as arguments for higher-order functions, such as filter() and map().
Example of a lambda function: double = lambda x: x * 2. Calling double(5) returns 10.
The filter() function takes a function and a list to return items that evaluate as True. Example filtering even numbers:
- my_list = [1, 5, 4, 6, 8, 11, 3, 12]
- new_list = list(filter(lambda x: (x % 2 == 0), my_list)) results in [4, 6, 8, 12].

Map Function

The map() function applies a function to all items in a list, returning a new list with the results.
Example to double each item in a list:
- my_list = [1, 5, 4, 6, 8, 11, 3, 12]
- new_list = list(map(lambda x: x * 2, my_list)) results in doubled values.

Functions in Python

A function is a block of reusable code that operates with input parameters and can return results.
Function calls reference functions defined elsewhere, including standard libraries and user-defined functions.

Variable Scope

Global variables exist outside functions and are accessible within and outside functions.
Local variables are defined within functions and limited to that function's scope.
Example:
- Global variable x = 5. Inside test1(), local x = 10 and calling prints both local and global values.

Nonlocal Variables

Nonlocal variables are used in nested functions, allowing access to variables in the enclosing scope that are not global.

Python Docstrings

Docstrings provide documentation for modules, functions, classes, or methods and are accessible as the __doc__ attribute.
Single-line docstrings should use triple quotes but occupy the same line for consistency.

Example function with a docstring:

def square(n):
    '''Takes in a number n, returns the square of n'''
    return n ** 2

Built-in Functions Documentation

Built-in function docstrings, like for print(), describe the function's parameters and output format, which helps with understanding usage.

Good Programming Practices

Emphasize writing well-structured and documented code using proper naming conventions for variables, functions, and classes.
Include README files, setup scripts, documentation for components, and tests to improve code usability and maintainability.
Consistent naming:
- Variable names: Use underscores (e.g., long_variable_name).
- Class names: Use CamelCase (e.g., LongClassName).

Python Modules and Packages

Python packages are directories containing multiple modules, typically including __init__.py files.
Popular Python packages for various applications:
- NumPy for scientific computing
- Pandas for data manipulation
- Matplotlib for data visualization
- Seaborn for statistical graphics
- Scikit-learn for machine learning
- Requests and Urllib3 for HTTP requests
- NLTK for natural language processing
- Pillow for image processing
- Pytest for testing code.

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Description

This quiz explores Python's lambda functions, also known as anonymous functions. You will learn how to define and use these functions as arguments in higher-order functions, along with practical examples to reinforce your understanding.