A legend from the deep awakens.
Meet the Seattle Kraken → https://t.co/to5BtVVPh1 pic.twitter.com/FQfOdaiGQQ

— Seattle Kraken (@NHLSeattle_) July 23, 2020

Problem: Given a collection. You want to create a new list based on all values in this collection. The code should run in a single line of code. How do you accomplish this? Do you need a lambda function?

Example: Given an array a = [1, 2, 3, 4]. You need to create a second array b with all values of a—while adding +1 to each value. Here’s your multi-liner:

a = [1, 2, 3, 4]

b = []

for x in a: b.append(x+1)

print(b)

# [2, 3, 4, 5]

How do you accomplish this in a single line of code?

Answer: No, you don’t need a lambda function. What you’re looking for is a feature called list comprehension. Here’s the one-liner expression that accomplishes this without the lambda function:

b = [x+1 for x in a]

print(b)

# [2, 3, 4, 5]

You can try this example yourself in our interactive code shell:

Let’s dive into some background information in case you wonder how list comprehensions work. Based on your question, I also suspect that you don’t completely understand lambda functions either, so I’ll also add another section about lambda functions. Finally, you’ll also learn about a third alternative method to solve this exact problem by using the lambda function in combination with Python’s built-in map() function!

So, stay with me—you’ll become a better coder in the process!

List Comprehension 101

List comprehension is a compact way of creating lists. The simple formula is [expression + context].

• Expression: What to do with each list element?
• Context: What elements to select? The context consists of an arbitrary number of for and if statements.

The example [x for x in range(3)] creates the list [0, 1, 2].

Have a look at the following interactive code snippet—can you figure out what’s printed to the shell? Go ahead and click “Run” to see what happens in the code:

I’ll explain both ways of generating a new list in the following.

Example: Say you want to filter out all customers from your database who earn more than $1,000,000. This is what a newbie not knowing list comprehension would do:

# (name, $-income)

customers = [("John", 240000), ("Alice", 120000), ("Ann", 1100000), ("Zach", 44000)] # your high-value customers earning <$1M

whales = []

for customer, income in customers: if income>1000000: whales.append(customer)

print(whales)

# ['Ann']

This snippet needs four lines just to create a list of high-value customers (whales)!

Instead, a much better way of doing the same thing is to use list comprehension:

whales = [x for x,y in customers if y>1000000]

print(whales)

# ['Ann']

List comprehension is dead simple when you know the formula.

“A list comprehension consists of brackets containing an expression followed by a for clause, then zero or more for or if clauses. The result will be a new list resulting from evaluating the expression in the context of the for and if clauses which follow it.”

Official Python Documentation

Here is the formula for list comprehension. That’s the one thing you should take home from this tutorial.

Formula: List comprehension consists of two parts.

‘[‘ + expression + context + ‘]’

The first part is the expression. In the example above it was the variable x. But you can also use a more complex expression such as x.upper(). Use any variable in your expression that you have defined in the context within a loop statement. See this example:

whales = [x.upper() for x,y in customers if y>1000000]

print(whales)

# ['ANN']

The second part is the context. The context consists of an arbitrary number of for and if clauses. The single goal of the context is to define (or restrict) the sequence of elements on which we want to apply the expression. That’s why you sometimes see complex restrictions such as this:

small_fishes = [x + str(y) for x,y in customers if y<1000000 if x!='John']

# (John is not a small fish...)

print(small_fishes)

# ['Alice120000', 'Zach44000']

Albrecht, one of the loyal readers of my “Coffee Break Python” email course, pointed out that you can break the formula further down using the following blueprint:

lst = [<expression> for <item> in <collection> if <expression>] 

A detailed tutorial on the topic is available for free at this tutorial on the Finxter blog.

Lambda Function 101

A lambda function is an anonymous function in Python. It starts with the keyword lambda, followed by a comma-separated list of zero or more arguments, followed by the colon and the return expression. For example, lambda x, y, z: x+y+z would calculate the sum of the three argument values x+y+z.

Here’s a practical example where lambda functions are used to generate an incrementor function:

Exercise: Add another parameter to the lambda function!

Watch the video or read the article to learn about lambda functions in Python:

Puzzle. Here’s a small code puzzle to test your skills:

def make_incrementor(n): return lambda x: x + n

f = make_incrementor(42)

print(f(0))

print(f(1))

To test your understanding, you can solve this exact code puzzle with the topic “lambda functions in Python” at my Finxter code puzzle app.

Find the detailed article on lambda functions here.

Alternative Method 3: map() + lambda + list()

Interestingly, there’s a third way of solving the above problem by using the map() function (and the lambda function):

# Method 3: map() + lambda + list()

a = [1, 2, 3, 4]

b = list(map(lambda x: x+1, a))

print(b)

# [2, 3, 4, 5]

You can learn about the map() function in my video tutorial here:

However, it would be better if you avoided the map function—it’s not readable and less efficient than list comprehension.

Where to Go From Here?

Enough theory, let’s get some practice!

To become successful in coding, you need to get out there and solve real problems for real people. That’s how you can become a six-figure earner easily. And that’s how you polish the skills you really need in practice. After all, what’s the use of learning theory that nobody ever needs?

Practice projects is how you sharpen your saw in coding!

Do you want to become a code master by focusing on practical code projects that actually earn you money and solve problems for people?

Then become a Python freelance developer! It’s the best way of approaching the task of improving your Python skills—even if you are a complete beginner.

Join my free webinar “How to Build Your High-Income Skill Python” and watch how I grew my coding business online and how you can, too—from the comfort of your own home.

Join the free webinar now!

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Nicole: Howdy, Guardians! I hope you’re all safe, healthy, and finding some fun out there. Thanks for keeping us company (not to mention each other) during these very unique days. I’ve felt so welcomed since stepping into the community from the Bungie side, and I’m excited to continue to explore ways to engage with and entertain you.

During our recent participation in the St. Jude Fundraiser marathon with our friends who drive the @GCXEvent, we discovered some new ways to recreate the streaming experience from our homes—which means developer commentary is coming soon to a screen near you!

You are cordially invited to dive into the Prophecy dungeon with some of the devs who created the experience.

Developer Deep Dive : Prophecy Dungeon

Tuesday, July 28 – 10AM Pacific

Come and watch us play our own game and tell you stories from its creation on the development floor. Learn more about our inspirations and motivations as we share snapshots from when it was just a work in progress. Join us in chat for the conversation!

We welcome you behind the curtain for a bit of fun, reminiscing, and insight into the life of game development.

I can’t wait to talk to you all again soon, but for now, see you then!

Destiny Dev Team: This past week Valve identified hardware configuration issues with 4 relays in their Chicago, Virginia, Stockholm, and Dubai data centers. In each case, the affected relay was unable to send traffic to one other relay in the same data center. If a connection to a peer went through both of those relays, then it would drop. Valve has fixed the configuration issues, and we have confirmed that the rate of disconnections in the affected areas has been reduced significantly.

These changes have reduced Beaver error codes significantly with players in the central and eastern United States of America being impacted the most. Beaver error codes are an indication of connectivity failure and can be caused by a wide range of issues. Some Beaver error codes are caused by local internet connectivity issues. If you still experiencing a lot of Beaver errors please use follow our Network Troubleshooting Guide and then report any further issues on our Help forum.

Back on the Menu

Destiny, the Official Cookbook released this week. It contains all kinds of Destiny inspired culinary concoctions waiting for you to whip up for breakfast, lunch, and dinner. Maybe even second breakfast if you are as hungry as the Drifter usually is. Yum yum yum yum yum.

Earlier this week, we gave you a behind the scenes look at how the cook book came to be. We partnered with Victoria Rosenthal to author this collection of recipes. She showed off her culinary and photography skills, dove deep into Destiny lore, and helped bring this fun cooking guide to life.

Twitch Prime

We have extended our Twitch Prime Rewards and now we’re in the bonus rounds. If you have an active Prime subscription, visit this page to link your Bungie.net account and claim your rewards. Once you are all set you can pay a visit to Amanda Holliday in the Tower to grab your new gear.

Here’s a look at what you can get this month:

• Tractor Cannon – Exotic Weapon
• Machinist’s Trove – Exotic Weapon Ornament
• Shadow Trespass – Exotic Ship
• Cavalcade – Legendary Sparrow

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DAM RESTORED

Our Player Support Team is tracking all of the known issues.

This is their report.

SEPTENARY ENCRYPTION EMBLEM

Last week, players were able to redeem their Bungie Day Septenary Encryption emblem in their Bungie.net Account’s Code Redemption History. An issue arose when players discovered that they had the option to choose a platform to redeem the emblem on. This wasn’t intentional and we have confirmed that the platform chosen doesn’t matter when players go to retrieve the emblem in-game.

Once players have redeemed their emblem, they should restart Destiny 2 and visit their Collections>Flair>General section to acquire the emblem.

KNOWN ISSUES

While we continue investigating various known issues, here is a list of the latest issues that were reported to us in our #Help Forum:

• Players can’t see their responses in chat on PC anymore.
• Duress and Egress lore may disappear if the Triumphs aren’t claimed.
• The South Paw controller scheme doesn’t allow Sparrows to boost.
• The High-Energy Fire Dawn Mod doesn’t allow Consumed with Light to stack twice when the Stacks on Stacks Dawn Mod is equipped.

For a full list of emergent issues in Destiny 2, players can review our Known Issues article. Players who observe other issues should report them to our #Help forum.

In a World

It’s been a minute since I’ve been in a movie theater, but with how many amazing Destiny movies are being made by the community, I don’t really care. This is where we get to stay in our PJs, burn our own popcorn, and pick our favorites to share with you! Let’s take a look at who caught our eye this week.

Movie of the Week: Killstreaks

Honorable Mention: Gotta Catch Them All

If one of these videos belongs to you, congrats! Now make sure you have your Bungie.net profile in the description of said video so we can send out your prized emblem.

That’s not the end of this week – we still have a Friday to survive – but this is how we bring “This Week At Bungie” to a close. While the journey to Beyond Light has been extended, we’re one week closer. That leaves a lot of time to talk about how the next expansion will change the game, as well as what you’ll want to accomplish between now and November.

I’m out next week, so be nice to Dmg while I’m gone.

<3 Cozmo

Microsoft saw an uptick in console sales during the last quarter of its 2020 financial year, reporting a 49 percent increase in hardware revenue due to an increase in consoles sold.

It’s a notable increase given that Microsoft’s last few quarterly reports have found hardware sales to be slowing. That jump also comes alongside other year-over-year increases for the Xbox brand during the quarter ending June 30, 2020.

Along with those year-over-year hardware gains, Microsoft says that Xbox content and services revenue also increased by $1.2 billion or 65 percent compared to the same quarter last year. As a whole, Microsoft says video game revenue increased $1.3 billion or 64 percent. Like many other companies right now, Microsoft credits that increase in spending (and record engagement) to on-going stay-at-home guidelines, as well as strength from third-party games.

Rocket League is officially going free-to-play when it launches on the Epic Games Store later in the summer, and following that shift new players on PC will no longer be able to download the game through Steam.

A heavier pivot toward the Epic Games Store has been somewhat expected since Rocket League developer Psyonix was acquired by Epic Games late last year, but today’s announcement isn’t full Epic Games Store exclusivity by any means.

For the most part, the Epic Games Store launch won’t affect current players of the game. Those that already play through Steam can continue to do so, and will also still see the same updates and new features as other platforms.

The only real EGS-centric change here is that, following the free-to-play update, new players won’t be able to download Rocket League through Steam and will instead have to turn to the Epic Games Store.

“Once Rocket League goes free to play, anyone who already owns Rocket League on any platform (including Steam) will be able to play and enjoy the game with full support for future updates and features,” explains a blog from Psyonix. “However, the Steam version will no longer be available to download for new players. To put it simply, wherever you play now (including Steam), you’ll still be able to play in the future.”

This rough timeline for a free-to-play launch comes 5 years into Rocket League’s lifetime, and follows a series of monetization changes and alterations launched in the months following Psyonix’s acquisition by Epic Games.