DEV Community: Vladimir Ignatev

🤔 Python Quiz: The `yield` Keyword

Vladimir Ignatev — Sun, 17 Dec 2023 14:00:00 +0000

Follow me to learn 🐍 Python in 5-minute a day fun quizzes!

You mastered iterables, didn't you? Then it's time for generators and the spell yield!

Quiz

Which code sample correctly uses the yield keyword in Python to make a count-down?

Sample 1

def count_down(number):
    while number > 0:
        yield number
        number -= 1

for count in count_down(5):
    print(count)

Sample 2

def count_down(number):
    for i in range(number):
        return i

for count in count_down(5):
    print(count)

Post your answer in the comments – is it 0 for the first sample or 1 for the second! As usually, the correct answer will be explained in the comments.

`zip` tricks ✨ in Python

Vladimir Ignatev — Sat, 16 Dec 2023 17:28:07 +0000

I noticed that my recent daily Python quiz about zip (I mean an iterable, not the .zip archive) received a decent attention. Thank you to all and every participant!

No wonder that iterables in Python is an essential tool for pocking up with data. There are few reasons made iterables popular and fun: performance, memory efficiency and expressive syntax.

One of the hardest things to understand in a zoo of iterables is zip, indeed. When I faced this animal first time I realized its' hidden power and got disappointed at the same time 🤭

Actually, zip serves two purposes:

First, is to "sew" two (or more) lists
Second is to tear them apart.

To illustrate this idea, I prepared the following example.

Suppose, that we have a column-oriented database (i.e. ClickHouse).

We are provided by 3 separate columns of data: first names, last names and professions. Every column contains data about persons who use our software. In real world, we could obtain this data from DBMS, APIs, physical files, user input etc.

# Three columns from the columnar database 
first_names = ["Elon", "Steve", "Bob"]
last_names  = ["Musk", "Jobs", "Dorf"] 
professions = ["builds rockets", "grows Macs", "helps startups"]

"Sew" two or more lists together and make a table from columns using `zip`

First scenario would be to merge them to make a single list of three persons, not three lists of every person field. In other words, we want to make a table from these 3 lists, containing 3 records. The same way as RDBMS (i.e. Postgres) stores data, and the same way people from OOP world think about it.

zip(first_names, last_names, professions)

This expression will return an iterable. You're free to materialize it into list as you wish and finally obtain the desired table in memory:

>>> table = list(zip(first_names, last_names, professions))
[('Elon', 'Musk', 'builds rockets'),
 ('Steve', 'Jobs', 'grows Macs'),
 ('Bob', 'Dorf', 'helps startups')]

Now, table[0] is a record containing Elon Musk who builds rockets, table[1] is a record containing Steve Jobs who enjoyed growing Macs and Apples (Rest in peace, dear Steve!) and vice versa.

Tear records apart and turn them back into columns

To achieve this, zip supports an asterisk syntax:

>>> cols = list(zip(*table))
[('Elon', 'Steve', 'Bob'),
 ('Musk', 'Jobs', 'Dorf'),
 ('builds rockets', 'grows Macs', 'helps startups')]

Back and again, we obtained columns instead of records! I.e., cols[2] represent professions and cols[0] contains only first names.

Iterables

Actually, desperately wrapping iterables into list is no good. In real world, columns or records could be very large and even non-fitting the memory. Every time we turn an iterable into a list, we allocate memory to store all the data.

Furthermore, columns/records could appear as iterables themselves, while we need additional processing or streaming the result to another physical device.

To avoid unnecessary allocations we have to keep iterables as iterables and not convert them into lists early.

Flame 🔥. Comment. Make cool things!

🤭 `zip` Python Quiz Of The Day

Vladimir Ignatev — Tue, 12 Dec 2023 19:06:33 +0000

The zip() function in Python is a powerful tool but often misunderstood by beginners. It's used to combine elements from multiple iterables (like lists, tuples) into tuples.

Quiz

Which one of these code samples correctly demonstrates the use of the zip() function in Python?

Sample 1

names = ['Alice', 'Bob', 'Charlie']
ages = [25, 30, 35]

for name, age in zip(names, ages):
    print(f"{name} is {age} years old.")

Sample 2

names = ['Alice', 'Bob', 'Charlie']
ages = [25, 30, 35]

for i in range(len(names)):
    print(f"{names[i]} is {ages[i]} years old.")

Post answer that you think is correct or just try it in the REPL!

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😄 Happy weekend! No daily Python quiz today and tomorrow

Vladimir Ignatev — Sat, 09 Dec 2023 18:11:10 +0000

Maintaining a work/life balance is essential when you do the Long run.

Python Quiz: 😮 Walrus operator in Python.

Vladimir Ignatev — Fri, 08 Dec 2023 14:00:00 +0000

Python's Walrus Operator (:=) was introduced in Python 3.8 as per PEP 572.

It allows for assignment expressions that enable you to assign values to variables as part of an expression. This feature can be quite handy but also a bit tricky for beginners to understand correctly.

One may think about := operator as an "in-place" assignment.
Look at this sample:

>>> a = (b := 5) * 4
20
>>> b
5

a here is assigned an expression 5 * 4, while the part of this expression, marked as b. After evaluation we get b equal to 5.

Quiz

Which code sample correctly demonstrates the use of Python's Walrus Operator (:=)?

Sample 1

# Using Walrus Operator in a while loop
a = [1, 2, 3, 4, 5]
while (n := len(a)) > 0:
    print(n)
    a.pop()

Sample 2

a = [1, 2, 3, 4, 5]
if n := len(a) > 3:
    print(f"List has {n} elements")

Post your answer in the comments – is it 0 for the first sample or 1 for the second! As usual, the correct answer will be explained in a comment.

🤔 Python Quiz: `with` or without?

Vladimir Ignatev — Thu, 07 Dec 2023 19:12:02 +0000

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The with statement in Python is a powerful feature for managing the lifetime of resources, ensuring they are properly acquired and released, thus promoting cleaner and more reliable code. It's primarily used in scenarios where a pair of related operations need to be executed, such as opening and closing a file, or acquiring and releasing a lock.

Quiz

Sample 1

file = open('example.txt', 'r')
content = file.read()
print(content)

Sample 2

# Using 'with' statement for file operations
with open('example.txt', 'r') as file:
    content = file.read()
print(content)

Post your answer in the comments – is it 0 for the first sample or 1 for the second! As usual, the correct answer will be explained in the comments.

🤔 Python Quiz: Unpacking Sequences in Python

Vladimir Ignatev — Wed, 06 Dec 2023 20:19:07 +0000

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Todays quiz is all about sequences and unpacking them. When you deal with list-type objects or tuples, sequence unpacking come to help! In this quiz guess a proper usage to unpack function arguments and print out user's score!

Sample 1

def process_data(*data):
    name, age, *scores = data
    print(f"Name: {name}, Age: {age}, Scores: {scores}")

process_data("Alice", 30, 75, 85, 90)

Sample 2

def process_data(*data):
    name, *age, scores = data
    print(f"Name: {name}, Age: {age}, Scores: {scores}")

process_data("Bob", 25, 80, 70, 95)

Which code snippet is correct? Post your answer in the comments – is it 0 for the first sample or 1 for the second! As usual, the correct answer will be explained later in comments.

🤔 Python Quiz: Introduction to `asyncio` in Python

Vladimir Ignatev — Tue, 05 Dec 2023 14:00:00 +0000

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For this quiz, I'll choose a topic related to the use of the asyncio module in Python, which is a more advanced concept but extremely useful in modern Python programming. This topic is covered by PEP 492 - Coroutines with async and await syntax, which is a fundamental part of asynchronous programming in Python.

In Python, the difference between asynchronous (async) and blocking code is central to how you write programs that perform tasks that can take a long time to complete, such as I/O operations.

Blocking Code:

Blocking code is the default mode of operation for Python; when the program encounters an operation, it must wait for the operation to complete before moving on to the next line of code.
If a blocking call is made (like input(), time.sleep(), or a network request), the entire program is stalled until that call returns.
In a single-threaded application, blocking I/O can make the program inefficient and unresponsive, especially in network programming or when dealing with files.

Asynchronous Code:

Asynchronous code allows the program to handle multiple operations without waiting for any single one to complete; while one operation is waiting, other operations can continue.
The asyncio library in Python provides the infrastructure for writing single-threaded concurrent code using coroutines, multiplexing I/O access over sockets and other resources, running network clients and servers, and other related primitives.
An async function is defined with the async def keyword, and it allows you to use await to pause the coroutine until an operation completes, while letting the event loop run other coroutines that are not paused.

Why It Matters:

Performance: Asynchronous code can provide a significant performance improvement for I/O-bound and high-level structured network code.
Efficiency: Async allows for more efficient use of system resources as you can handle more tasks with fewer threads.
Responsiveness: In user-facing applications, such as web applications, async programming can prevent the application from becoming unresponsive.
Scalability: Asynchronous applications can scale better, as they can handle many simultaneous connections.

Quiz

Which code sample correctly uses the asyncio module in Python for asynchronous programming?

Sample 1

import asyncio

async def main():
    print("Hello")
    await asyncio.sleep(1)
    print("World")

asyncio.run(main())

Sample 2

import asyncio

def main():
    print("Hello")
    asyncio.sleep(1)
    print("World")

asyncio.run(main())

Post your answer in the comments – is it 0 for the first sample or 1 for the second! As usual, the correct answer will be explained in the comments.

Batch photo tagging for stock websites using GPT-4 Vision

Vladimir Ignatev — Mon, 04 Dec 2023 20:19:36 +0000

I'm eager to share with you the piece of software I've created with an intent to help my wife with her photo business.

She is a photographer and from time to time she uploads photos to stock sites. Some batches contain 100+ photos that makes tagging of them an endless nightmare.

I wrote a command-line utility that uses GPT-4 Vision to bulk tag photos and installed on her Mac to make her a bit happier 🌷!

Source code available on GitHub.

Push the "Like" button if you want the full story, code samples and tutorials for beginners!

🤔 Python Quiz: Traveling Time Zones in Python 🕔

Vladimir Ignatev — Mon, 04 Dec 2023 14:00:00 +0000

The topic for todays quiz is "Handling Time Zones in Python" covered by PEP 431 and PEP 495. These PEPs discuss improvements in timezone support in Python's datetime module, making it a relevant and somewhat challenging topic for beginners.

Follow me to learn 🐍 Python in 5-minute a day fun quizzes!

Quiz

Which code sample correctly handles time zones in Python?

Sample 1

from datetime import datetime, timezone

utc_time = datetime(2023, 12, 3, 10, 0, 0, tzinfo=timezone.utc)
local_time = utc_time.astimezone()
print(local_time)

Sample 2

from datetime import datetime

local_time = datetime(2023, 12, 3, 10, 0, 0)
utc_time = local_time.astimezone("UTC")
print(utc_time)

Post your answer in the comments – is it 0 for the first sample or 1 for the second! As usual, the correct answer will be explained in a comment.

🤔 Python Quiz: Enums in Python

Vladimir Ignatev — Sun, 03 Dec 2023 14:17:25 +0000

It's time for the next Python Quiz!

Follow me to learn 🐍 Python 5-minute a day by answering fun quizzes!

Today's topic is enum module. PEP 435 introduced the enum module in Python 3.4, providing support for enumerations in Python.

Enumerations are sets of symbolic names (members) bound to unique, constant values. They are used to make code more descriptive and readable. Enums help to address specific variant or case in your code, without actually relying on the value corresponding to that variant.

Quiz

Which one of these code samples correctly demonstrates the use of Enums in Python?

Sample 1

from enum import Enum

class Color(Enum):
    RED = 1
    GREEN = 2
    BLUE = 3

favorite_color = Color.RED
print(favorite_color.name, favorite_color.value)

Sample 2

class Color:
    RED = 1
    GREEN = 2
    BLUE = 3

favorite_color = Color.RED
print(favorite_color.name, favorite_color.value)

Post your answer in the comments – is it 0 for the first sample or 1 for the second! As usual, the correct answer will be explained in the comment.

Or go to the previous quiz instead

Like the quiz? Don't miss the quiz I prepared for tomorrow! Follow me and learn 🐍 Python 5-minute a day!

🤔 Python Quiz: ⚗️ Dicts Alloy

Vladimir Ignatev — Sat, 02 Dec 2023 18:41:42 +0000

Follow me to learn 🐍 Python in 5-minute a day fun quizzes! Find previous quiz here.

Python 3.9 introduced new operators for dictionary merging. You'll learn more about making alloys from your dicts by reading the original PEP-0584. PEP-0584 simplifies dictionary operations, enhancing Python's ease of use and readability..

Quiz

Which one of these code samples correctly demonstrates the use of Python's dictionary merging as guided by PEP 584?

Sample 1

dict1 = {'a': 1, 'b': 2}
dict2 = {'b': 3, 'c': 4}
merged_dict = dict1 | dict2

Sample 2

dict1 = {'a': 1, 'b': 2}
dict2 = {'b': 3, 'c': 4}
merged_dict = dict1 + dict2

Post your answer in the comments! 0 if you think that Sample 1 is correct, 1 otherwise. As usually, the correct answer will be explained in the first comment.

DEV Community: Vladimir Ignatev

🤔 Python Quiz: The `yield` Keyword

Quiz

Sample 1

Sample 2

`zip` tricks ✨ in Python

"Sew" two or more lists together and make a table from columns using zip

Tear records apart and turn them back into columns

Iterables

🤭 `zip` Python Quiz Of The Day

Quiz

Sample 1

Sample 2

😄 Happy weekend! No daily Python quiz today and tomorrow

Python Quiz: 😮 Walrus operator in Python.

Quiz

Sample 1

Sample 2

🤔 Python Quiz: `with` or without?

Quiz

Sample 1

Sample 2

🤔 Python Quiz: Unpacking Sequences in Python

Sample 1

Sample 2

🤔 Python Quiz: Introduction to `asyncio` in Python

Quiz

Sample 1

Sample 2

Batch photo tagging for stock websites using GPT-4 Vision

🤔 Python Quiz: Traveling Time Zones in Python 🕔

Quiz

Sample 1

Sample 2

🤔 Python Quiz: Enums in Python

Quiz

Sample 1

Sample 2

🤔 Python Quiz: ⚗️ Dicts Alloy

Quiz

Sample 1

Sample 2

"Sew" two or more lists together and make a table from columns using `zip`