Even though first-party support for the Wii U came to a halt a number of years ago, that hasn’t stopped third-party developers and publishers from pumping out new releases for Nintendo’s previous generation of console hardware. PixelHeart – a publisher and distributor of retro and next-generation games – has just put up pre-orders for two new Wii U physical releases.

The first is a hard-copy of the SHMUP Collection (containing Satazius Next and Armed 7 DX, and due out on 15th May 2020) and the other one is Finding Teddy II: Definitive Edition (arriving 17th April 2020). As noted by DualShocker, both of these releases are the European versions, so you’ll need to have access to a system from this region in order to play them.

Both games cost €29,90 and are limited to 3,000 units each. If you’re not interested in owning these titles on Wii U, there’s always the option to purchase them on the Switch as well for the same price. Could these be the very last physical Wii U games ever released? Tell us what you think below and if you would be interested in adding either or both of these titles to your physical collection.

This Week at Bungie, we prepare for the worthy.

Now, we have some housekeeping to do before we arm an ancient Warmind. Let’s get to it.

#TrialsReturns

Moments after the announcement that Trials of Osiris would return with Season of the Worthy, we witnessed numerous Guardians sharing their favorite memories from this beloved corner of the PvP endgame. Moments of spectacle, joy, heartbreak, insanity, and everything in between. Trials of Osiris was the source of some awesome community highlights—a thing that some of our newer Guardians may have yet to experience. We’d love to see more of your stories and bring them into the scene.

If your video is selected, you and your fireteam will take home a Movie of the Week emblem. Make sure to include links to the Bungie.net profiles of every team member.

Power Gains

With each new Season, you’re faced with new challenges that require a bit of Power acquisition to take on. In Season of Worthy, you’ll be challenged in not only Trials of Osiris, but in Legendary Lost Sectors and Grandmaster Nightfalls. Here’s a quick update from the Dev team on what’s changing on day-one, and what our plans are for a mid-season update:

Dev team: We’re raising the ‘cap’ for gear drops 40 points—powerful gear will now drop up to 1000, with pinnacle drops going up to 1010. The soft cap has also been effectively raised 50 points. Gear drops from nearly all sources will continue to be upgrades until 950 Power, and powerful reward sources will not be required to progress to 950. We’re looking to present an element of gear progression available each Season, as well as prepare underlying systems for future updates like the forthcoming one for Legendary weapons mentioned by Luke Smith in the Director’s Cut ‘Weapons Forever’ section.

We’re also looking to make some quality of life updates in the pinnacle band. Starting in 2.8.1. (coming mid-Season), we’ll be upgrading some existing powerful rewards to pinnacle rewards. These are the weekly Crucible, Strike, and Gambit challenges, as well as the weekly clan engram. With this change, we want to increase the total number of pinnacle power sources in the game, broaden pinnacle drop access, as well as increase the pools of items that can drop in the pinnacle band.

Slot imbalances can also affect pinnacle progression. When we say slot imbalance, this could be explained as those times you have a chest piece drop from pinnacle sources a few times in a row. We’ve been looking at player feedback for some time, and are investigating a few approaches to the problem space. We’re looking to have an update on that at a later date. Until then, we hope the additional sources will help you on your climb.

While we have the Dev team here, they also wanted to give an update on Artifact Power for Trials of Osiris.

Dev team: With Trials just around the corner, we wanted to address the “Artifact Power problem” as quickly as we could. As Luke said last week, our short-term fix is to disable the Artifact’s Power bonus while in Trials and Iron Banner. Unfortunately, Season of the Worthy has already been released for certification, so we won’t be able to disable the Artifact’s Power for the first Trials weekend. We have the fix in-house to disable it and are testing it this week, and hope to deploy it on Tuesday, March 17. We really wish we could have gotten it in for the launch weekend, but we also expect the first Trials weekend to be the one impacted by the Artifact the least. Players will have much less time to increase their Artifact Power, so the majority will be close to each other outside of Pinnacle drops.

Our long-term plan is to enable a Power cap for Trials and Iron Banner and we’re investigating the work required for this. This will roll out no earlier than midway through Season of the Worthy, but we don’t have a firm date yet—we’ll make sure to communicate it when we do! We also plan to look at the damage curves for Power-enabled PvP modes to determine what, if any, adjustments should be made. Assuming we discover it’s necessary, the timeline for a change is still TBD. With both changes, we plan to provide more detailed write-ups before they go live, explaining the details of the change and the design philosophy behind why we are making those decisions.

Just for clarity, I’ll echo Luke’s statement from last week: we’re going to disable the Artifact Power bonus in Trials and Iron Banner until we can implement a new Power cap system for those playlists. I hope you all enjoy Season of the Worthy, and may your run to the Lighthouse be swift and merciless.

Season of the Worthy: Eververse Update

With the turn of each Season, we hope to keep players up to date on how the Eververse Store is evolving. This Season, we have a few changes concerning Bright Engrams, and a new path to directly purchasing some previously featured Eververse items.

Bright Engrams

“We want players to know what something costs before they buy it. Bright Engrams don’t live up to that principle so we will no longer be selling them on the Eververse Store, though they will still appear on the Free Track of the Season Pass.”

This Season, we are continuing to focusing our efforts on direct purchasing through the Eververse Store.

Daily Rotation of Returning Items

In the place of Bright Engrams, a new module will become available on the Eververse Store starting in Season of the Worthy. This daily-rotating module will feature one item from a small selection of ships, Sparrows, Ghosts, and finishers that were offered in previous Seasons. These items will be available to purchase directly for Silver at a discount from the original price.

Aside from these changes, there aren’t any other major shifts coming for Eververse. We’ll be monitoring the conversation through launch and beyond, and will be sure to update you before any large changes come. Here’s a quick preview of some upcoming items coming with Season of the Worthy:

Hunter Finisher

Titan Finisher

 Warlock Finisher

The Final Preview (of Patch Notes)

Over the last few weeks, we’ve been giving some previews how your sandbox will be evolving in Season of the Worthy. Not just weapon tuning, but the ability to change the Elemental Affinity on your armor pieces. This week, we’ll be taking a wider look at Destiny 2 Update 2.8.0. Exotic armor tuning for PvE and PvP, UI updates, bug fixes, and more…

Exotic Armor

While this list is pretty lengthy, we’ll have more patch notes to share with you next Tuesday around 9 AM PDT, an hour before Season of the Worthy begins.

Some of you may be asking, “Wait, 10 AM? Don’t patches usually ship at 9 AM?” Daylight Saving Time begins on Sunday, March 8. If your region takes part in jumping forward, your weekly reset time will be an hour later than you’re used to. More information from the Player Support team below.

Systems Check

Before we dive headfirst into Season of the Worthy, we have a patch to ship. Destiny Player Support has your itinerary in hand, and a quick list of some resolved issues.

A NEW SEASON

Next week, Season of Dawn ends and Season of the Worthy kicks off with the release of Destiny 2 Update 2.8.0. Please see below for the rollout timeline.

• 8 AM PDT (1500 UTC): Destiny service maintenance begins.
• 8:45 AM PDT (1545 UTC): Destiny 2 is taken offline on all platforms.
• 9 AM PDT (1600 UTC): Destiny 2 Update 2.8.0 begins rolling out across all platforms and regions. Players will be able to log back into Destiny 2 at 10:01 AM PDT.
• 10:01 AM PDT (1701 UTC): Destiny 2 is back online on all platforms; Season of The Worthy begins.
• 12 PM PDT (1900 UTC): Destiny service maintenance concludes.

UPCOMING RESOLVED ISSUES, PT. 2

Below is a continuation of a list of issues that will be resolved when Season of the Worthy and Update 2.8.0 become available on March 10:

• Hunter’s Tempest Strike melee ability can now be performed when using PC controls where Sprint is set to “Hold.”
• Character subclasses with ranged melee abilities will now count towards Melee Kill bounties and Triumphs. These include Titan Hammer Throw, Hunter Throwing Knives and Corrosive Smoke Bomb, and Warlock Celestial Fire and Ball Lightning.
• The Fastidious Miser Triumph will now correctly progress and complete for players who’ve found all 30 Ascendant Chests across the three Curse Weeks in the Dreaming City, and have claimed those corresponding Triumphs.
• Weekly Strike bounties for Hive and Vex boss kills will now award progress to players for killing Savathûn’s Song, Xol, and Dendron the Root Mind.

While Update 2.8.0 is released to the world, Destiny Player Support will be on standby in the #Help forum, ready to assist anyone who is experiencing issues.

Dawn Comes to an End

Movie of the Week: Creatures of Destiny: A Nature Documentary

Honorable Mention: This player should be banned for such an unsatisfying montage

Honorable Mention: Riven’s Heart Theme Keyboard Cover

It’s crazy to think that next week a new Season begins. It feels like just yesterday we were watching you all explore the Corridors of Time. It’s no secret that I’m pretty excited for Trials to return, and I’m also looking forward to see you share your memories with the #TrialsReturns hashtag.

See you next week. Maybe we’ll bump into each other on our way to the Lighthouse. No hard feelings when you lose, okay?

Cheers,

Dmg04

Today Mojang brings another round of fixes for Beta players on Bedrock.

Remember that only those on Xbox One / Windows 10 / and Android may participate in the Beta builds.  You will not be able to join Realms or non-beta players worlds and you will not be able to open worlds opened in the Beta in earlier/current stable builds of Bedrock.

• Crashes/Performance
  
  • Fixed several crashes that could occur during gameplay
  • Fixed a crash that could occur when trying to enchant fishing rods

• General
  
  • Marketplace ratings now appear correctly when scrolling (MCPE-60287)

•  Gameplay
  
  • Parity: Blocks will now lose their waterlogged state when pushed by a piston
  • Kelp will now keep growing after being partially broken by a piston, and the piece below will have a maximum random age of 24 (MCPE-57330)
  • Blue Wither Skulls will once again break Obsidian (MCPE-63223)
  • Ender Dragon Fireball attacks no longer cause excessive damage (MCPE-40344)
  • Hopper mine carts will now drop hoppers and mine carts when broken with a ranged weapon (MCPE-55859)
  • Fixed several crafting recipe issues:
    
    • Multiple Honey Blocks can be crafted in the 2×2 crafting grid (MCPE-63081)
    • Crafting Multiple Honey Blocks returns the correct amount of items to the player (MCPE-63461, MCPE-58579)

• Mobs
  
  • Parity: Cured Zombie Villagers can now offer discounted trades (MCPE-47040)
  • Hostile mobs will now correctly seek out and jump on turtle eggs (MCPE-36244)
  • Cured Zombie Villagers no longer inherit XP unexpectedly, which would prevent them from acquiring a new profession (MCPE-48712)
  • Villagers will no longer become preoccupied with sharing carrots (MCPE-32627)
  • Vindicators that spawn in Woodland Mansions will now use the spawned event and become hostile before being attacked (MCPE-43208)
  • Villagers now have a chance to offer Trident Enchantment books as trades (MCPE-35406)
  • Creepers in boats now deal damage to players nearby
  • Wolves will once again heal when fed meat (MCPE-63205)

Broomstick League is Now Available on Steam Early Access and is 10% off!*

Equipped with a broomstick, a wand and nerves of steel, players must hone their flying skills and use magic to dodge enemies, defend their goal, and pull off incredible plays in Broomstick League. Soar high through the magical arenas as you try to outscore the competition and gain victory over your opponents.

*Offer ends March 12 at 10AM Pacific Time

The Entertainment Software Association has posted an updated statement on June’s E3 plans as concerns about the ongoing COVID-19 coronavirus outbreak continue to rise.

In that statement, the ESA says that E3 is currently still planned to take place in Los Angeles on June 9-11, but that it is actively “monitoring and evaluating the situation daily.”

The ESA’s updated comments come hours after the county of Los Angeles declared a state of emergency, a step that ultimately allows local governments to better access and allocate funds for preventative measures and continue to monitor the virus’ spread. Los Angeles reported its first COVID-19-related death today, and has reported seven confirmed cases so far.

“The health and safety of our attendees, exhibitors, partners, and staff is our top priority,” reads the statement. “While the ESA continues to plan for a safe and successful E3 show June 9-11, 2020—we are monitoring and evaluating the situation daily. Our E3 team and partners continue to monitor COVID-19 via the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO). We are actively assessing the latest information and will continue to develop measures to further reduce health risks at the show.”

The Gamasutra Job Board is the most diverse, active and established board of its kind for the video game industry!

Here is just one of the many, many positions being advertised right now.

Location: Pittsburgh, Pennsylvania​

Our artists honor the unique aesthetic vision of each project and work to make all aspects of the experience beautiful. The team is comprised of 2D/conceptual artists, 3D modelers, technical and effects artists, and animators.  We are seeking a talented VFX Game Artist to work on projects ranging from online worlds and handheld games to virtual reality experiences and themed interactive attractions.

You must demonstrate the ability to collaborate well with a multi­disciplined team, communicating constructively, both verbally and in writing, in order to create engaging and visually compelling game assets.  The ideal candidate will have to be self-motivated and a collaborative team player who is able to work closely with the Art Director to be responsible for large sections of the game.

Our ideal candidate will have the ability to handle both technical and artistic issues during game development, as well as be able to work quickly in a team atmosphere with schedules and reliable milestone delivery, all while demonstrating the ability to respond professionally to feedback and art direction.   This candidate should be highly creative, able to conceptualize, and possess an eye for motion.  Passion for effects work and game visuals, with the ability to reach a wide range of styles within the media are crucial.

You will design, create and implement dynamic and dramatic in-game special effects in-engine (explosions, pyro, UI effects, magic, environmental effects, etc). You will work closely with designers, engineers, artists, and audio to inspire gameplay ideas and ensure that the effects meet design needs and stunning visuals. Our candidate should be comfortable using Maya, Photoshop, Unreal and/or Unity to create and implement VFX.

We’re looking for someone excited about cross­-disciplined collaboration and making great games with us!

REQUIREMENTS:

• Portfolio of work must be available for review, displaying the use of particle systems, shaders, and mesh effects
• Understanding of optimization limitations and methodology
• Display excellent communication skills, both verbal and visual
• Understanding of various methodologies for VFX creation
• Experience in Unreal and/or Unity engine for the creation of VFX
• Understanding of VFX/PostFX integration and performance impacts

DESIRED SKILLS:

• Concept art foundational skills
• Houdini experience
• Knowledge of shader creation or shader based workflows

EDUCATIONAL BACKGROUND:

•  BS/BA/BFA degree in fine arts, animation, visual communication, or similar

Interested? Apply now.

Whether you’re just starting out, looking for something new, or just seeing what’s out there, the Gamasutra Job Board is the place where game developers move ahead in their careers.

Gamasutra’s Job Board is the most diverse, most active, and most established board of its kind in the video game industry, serving companies of all sizes, from indie to triple-A.

Looking for a new job? Get started here. Are you a recruiter looking for talent? Post jobs here.

The Castlevania series has a rich history on Nintendo consoles ever since the original game came first to the Japanese Famicom Disk System way back in 1986, and then to the NES a year later. There may be a significant release or two from Konami’s vampire-killing catalogue still missing from Nintendo platforms (we’re looking at you, Symphony of the Night), but the vast majority of the series can be found on Nintendo consoles. Given the release of Netflix’s third Castlevania season today, we thought it might be fun to look back at the franchise.

But where should you start if you’re new to the Castlevania series? Which Castlevania game is the best? Those are tough questions, but we’ve done our best to whip up a ranked list of the best Castlevania games (on Nintendo consoles) below. The series has many high points (and a couple of very low ones, too) and come in two distinct flavours: the more straightforward right-to-left style of the original games or the more expansive brand of Koji Igarashi-produced games (sometimes referred to as ‘Igavanias’) which combined spiritually with Nintendo’s Metroid series to birth an entire genre of ‘Metroidvania‘ video games.

For Switch owners the Castlevania Anniversary Collection should obviously be your first port of call, and there’s always Koji Igarashi’s non-affiliated Bloodstained: Ritual of the Night once you’ve exhausted all the Belmonts below. The Switch version isn’t perfect, but it is much improved since launch and is arguably the closest thing fans will get to Symphony of the Night on Switch until Konami decides to put Symphony of the Night on Switch.

We’ve included a couple of spin-offs and oddities, but that’s more than enough waffle. Wipe away those bloody tears, and let’s go kill us some vampires.

Publisher: Konami / Developer: Konami

Release Date: 18th Nov 2008 (USA) / 20th Mar 2009 (UK/EU)

We start with a spin-off. Set in the Castlevania universe, this 2008 Wii game brought all your favourite characters and monsters together for a momentously rubbish one-on-one 3D fighter with awful controls and questionable character designs. Castlevania Judgment was panned by critics and fans alike on release and time has done nothing to heal the wounds this one inflicted. A miserable pile, indeed.

Publisher: Konami / Developer: Konami

Release Date: 10th Dec 1989 (USA) / 10th Dec 1989 (UK/EU)

The first entry for the series on the Game Boy, and one best left forgotten, Castlevania: The Adventure is a turgid, terminally sluggish approximation of the series’ classic gameplay with repetitive, bland level design. Given the host console’s limitations, you might be tempted to give it the benefit of the doubt, but the sequel would show what the platform was truly capable of and expose this for the horror that it is. Do yourself a favour, skip this and start your portable Castlevania adventure with Belmont’s Revenge.

Publisher: Konami / Developer: Konami

Release Date: Feb 1988 (USA) / Nov 1988 (UK/EU)

Available on Switch as part of Konami’s Arcade Classics Anniversary Collection, Haunted Castle is an odd duck. Made exclusively for arcades, it occupies a strange middle ground somewhere between homage, parody and port and sees Simon Belmont (with a sprite which stands a quarter of the screen tall) rescuing his new bride from the villainous clutches of the Count. The music is by far the best thing about it, but despite looking superficially ‘better’ than the original, it’s an unfairly punishing arcade experience designed to empty your pockets of shiny coins. As such, there’s not much fun to be had and ultimately it’s not a patch on the original.

If you’re interested you can check out the differences between the original NES game, its VS Castlevania arcade port and Haunted Castle in this video.

Publisher: Konami / Developer: Konami Computer Entertainment Nagoya

Release Date: 11th Mar 1998 (USA) / 11th Mar 1998 (UK/EU)

Without knowing that this was the third Castlevania for Game Boy, you could be forgiven for thinking this was the second game before Konami perfected things with Belmont’s Revenge. But no, Castlevania Legends was a late release for the ageing console (1997 in Japan, 1998 in the West) – the third and final entry and a less than auspicious farewell to Nintendo’s 8-bit handheld. Following the release of the towering Symphony of the Night on PlayStation would have been an unenviable task, to be sure, but even taking into account the platform’s inherent limitations this is an intense disappointment. With poor animation, lacklustre sprite work and equally unimpressive level design, it’s hard to believe that this came a whopping seven years after its fantastic predecessor.

Simply put, it wasn’t good enough at the time, and despite being a sought-after collectors item these days, it’s only got worse with age. Avoid.

Publisher: Konami / Developer: Konami

Release Date: 31st Dec 1998 (USA) / 11th Mar 1999 (UK/EU)

A flawed stab at a polygonal 3D Castlevania, this isn’t ‘bad’ as much as ‘crushingly average’. Launching several years into the N64’s cycle in 1999, players expected better from a 3D game at the dawning of the new millennium. Camera issues were a perennial problem for games of the era, but the best Castlevania titles have always been characterised by tight controls and Castlevania (yes, it eschewed the ’64’ colloquially appended to its title) simply wasn’t up to snuff. We respect it – from afar – but this one’s probably best left in the crypt.

Publisher: Konami / Developer: Konami

Release Date: 30th Nov 1999 (USA) / 3rd Mar 2000 (UK/EU)

This second N64 entry released less than a year after the first and actually includes the entire first game as an unlockable bonus once you’ve completed the prequel adventure. Castlevania: Legacy of Darkness is essentially the game its predecessor should have been and would no doubt be a DLC release with umpteen patches these days. It features numerous gameplay tweaks and also uses the Expansion Pak for improved visuals, but paying full price for this after putting down hard cash for its predecessor at the start of the year was painful, even for series devotees. Those N64 carts were pricey back in the day, and even in its polished form Legacy of Darkness is a long way from ‘classic’ status, in spite of our residual affection for it.

Publisher: Konami / Developer: Konami

Release Date: 29th Oct 2007 (USA) / 19th Oct 2007 (UK/EU)

Another game we have fond memories of, despite itself. Castlevania II: Simon’s Quest is obtuse, infuriating and downright cheap at times… but it’s got a killer soundtrack and admirably changes things up by building on the original game with new ideas, including a day/night cycle and an intriguing (if ultimately frustrating) non-linear approach. Back in the day it would have been an absolute nightmare, and we totally understand people who lose patience with it, but if you’re not opposed to sitting down with a walkthrough and making use of save states, we’d recommend giving Simon’s Quest another chance. The soundtrack alone makes it worth a playthrough.

Publisher: Konami / Developer: Konami

Release Date: 1987 (UK/EU)

This MSX2 version of Castlevania was developed in tandem with the NES game and features many similarities as well as some fascinating differences from the game you’re probably familiar with. For example, it wasn’t possible to implement scrolling in the MSX2 version so each level is divided into single screens that you move between. If you’re interested in a side-by-side comparison, check out this overview video from Splash Wave.

So what’s this doing on a list of Castlevania games for Nintendo consoles, you ask. Well, Vampire Killer released on the Wii U Virtual Console in Japan, so while we may not have had the pleasure in the West, it has technically appeared on a Nintendo platform. Ergo, it’s inclusion here.

Publisher: Konami / Developer: Konami

Release Date: 1st Sep 1995 (USA) / 1st Sep 1995 (UK/EU)

Known as Vampire’s Kiss in the EU, Castlevania: Dracula X is a Super NES remake of the PC Engine original Rondo of Blood, it doesn’t stand up to comparison with the game on which it is based, although it’s certainly not bad taken in isolation. It offers solid, old-school Castlevania fare and is worth investigating if you’ve chewed your way through better games in the series (most notably the original Rondo of Blood). If you’re new to the series, we wouldn’t start here, though.

Killer box art, mind.

Today, I stumbled upon this beautiful regex problem:

Given is a multi-line string and a regex pattern. How to find all lines that do NOT contain the regex pattern?

I’ll give you a short answer and a long answer.

The short answer is to use the pattern '((?!regex).)*' to match all lines that do not contain regex pattern regex. The expression '(?! ...)' is a negative lookahead that ensures that the enclosed pattern ... does not follow from the current position.

So let’s discuss this solution in greater detail. (You can also watch my explainer video if you prefer video format.)

Detailed Example

Let’s consider a practical code snippet. I’ll show you the code first and explain it afterwards:

import re

s = '''the answer is 42

the answer: 42

42 is the answer

43 is not

the answer

42''' for match in re.finditer('^((?!42).)*$', s, flags=re.M): print(match) '''

<re.Match object; span=(49, 58), match='43 is not'>

<re.Match object; span=(59, 69), match='the answer'> '''

You can see that the code successfully matches only the lines that do not contain the string '42'.

How can you do it?

The general idea is to match a line that doesn’t contain the string ‘42', print it to the shell, and move on to the next line.

The re.finditer(pattern, string) accomplishes this easily by returning an iterator over all match objects.

The regex pattern '^((?!42).)*$' matches the whole line from the first position '^' to the last position '$'. If you need a refresher on the start-of-the-line and end-of-the-line metacharacters, read this 5-min tutorial.

In between, you match an arbitrary number of characters: the asterisk quantifier does that for you. If you need help understanding the asterisk quantifier, check out this blog tutorial.

Which characters do you match? Only those where you don’t have the negative word '42' in your lookahead. If you need a refresher on lookaheads, check out this tutorial.

The lookahead itself doesn’t consume a character. Thus, you need to consume it manually by adding the dot metacharacter . which matches all characters except the newline character '\n'. As it turns out, there’s also a blog tutorial on the dot metacharacter.

Finally, you need to define the re.MULTILINE flag, in short: re.M, because it allows the start ^ and end $ metacharacters to match also at the start and end of each line (not only at the start and end of each string). You can read more about the flags argument at this blog tutorial.

Together, this regular expression matches all lines that do not contain the specific word '42'.

In case you had some problems understanding the concept of lookahead (and why it doesn’t consume anything), have a look at this explanation from the matching group tutorial on this blog:

Positive Lookahead (?=…)

The concept of lookahead is a very powerful one and any advanced coder should know it. A friend recently told me that he had written a complicated regex that ignores the order of occurrences of two words in a given text. It’s a challenging problem and without the concept of lookahead, the resulting code will be complicated and hard to understand. However, the concept of lookahead makes this problem simple to write and read.

But first things first: how does the lookahead assertion work?

In normal regular expression processing, the regex is matched from left to right. The regex engine “consumes” partially matching substrings. The consumed substring cannot be matched by any other part of the regex.

Figure: A simple example of lookahead. The regular expression engine matches (“consumes”) the string partially. Then it checks whether the remaining pattern could be matched without actually matching it.

Think of the lookahead assertion as a non-consuming pattern match. The regex engine goes from the left to the right—searching for the pattern. At each point, it has one “current” position to check if this position is the first position of the remaining match. In other words, the regex engine tries to “consume” the next character as a (partial) match of the pattern.

The advantage of the lookahead expression is that it doesn’t consume anything. It just “looks ahead” starting from the current position whether what follows would theoretically match the lookahead pattern. If it doesn’t, the regex engine cannot move on. Next, it “backtracks”—which is just a fancy way of saying: it goes back to a previous decision and tries to match something else.

Positive Lookahead Example: How to Match Two Words in Arbitrary Order?

What if you want to search a given text for pattern A AND pattern B—but in no particular order? If both patterns appear anywhere in the string, the whole string should be returned as a match.

Now, this is a bit more complicated because any regular expression pattern is ordered from left to right. A simple solution is to use the lookahead assertion (?.*A) to check whether regex A appears anywhere in the string. (Note we assume a single line string as the .* pattern doesn’t match the newline character by default.)

Let’s first have a look at the minimal solution to check for two patterns anywhere in the string (say, patterns ‘hi’ AND ‘you’).

>>> import re

>>> pattern = '(?=.*hi)(?=.*you)'

>>> re.findall(pattern, 'hi how are yo?')

[]

>>> re.findall(pattern, 'hi how are you?')

['']

In the first example, both words do not appear. In the second example, they do.

Let’s go back to the expression (?=.*hi)(?=.*you) to match strings that contain both ‘hi’ and ‘you’. Why does it work?

The reason is that the lookahead expressions don’t consume anything. You first search for an arbitrary number of characters .*, followed by the word hi. But because the regex engine hasn’t consumed anything, it’s still in the same position at the beginning of the string. So, you can repeat the same for the word you.

Note that this method doesn’t care about the order of the two words:

>>> import re

>>> pattern = '(?=.*hi)(?=.*you)'

>>> re.findall(pattern, 'hi how are you?')

['']

>>> re.findall(pattern, 'you are how? hi!')

['']

No matter which word “hi” or “you” appears first in the text, the regex engine finds both.

You may ask: why’s the output the empty string? The reason is that the regex engine hasn’t consumed any character. It just checked the lookaheads. So the easy fix is to consume all characters as follows:

>>> import re

>>> pattern = '(?=.*hi)(?=.*you).*'

>>> re.findall(pattern, 'you fly high')

['you fly high']

Now, the whole string is a match because after checking the lookahead with ‘(?=.*hi)(?=.*you)’, you also consume the whole string ‘.*’.

Negative Lookahead (?!…)

The negative lookahead works just like the positive lookahead—only it checks that the given regex pattern does not occur going forward from a certain position.

Here’s an example:

>>> import re

>>> re.search('(?!.*hi.*)', 'hi say hi?')

<re.Match object; span=(8, 8), match=''>

The negative lookahead pattern (?!.*hi.*) ensures that, going forward in the string, there’s no occurrence of the substring 'hi'. The first position where this holds is position 8 (right after the second 'h'). Like the positive lookahead, the negative lookahead does not consume any character so the result is the empty string (which is a valid match of the pattern).

You can even combine multiple negative lookaheads like this:

>>> re.search('(?!.*hi.*)(?!\?).', 'hi say hi?')

<re.Match object; span=(8, 9), match='i'>

You search for a position where neither ‘hi’ is in the lookahead, nor does the question mark character follow immediately. This time, we consume an arbitrary character so the resulting match is the character 'i'.

Where to Go From Here?

Summary: You’ve learned that you can match all lines that do not match a certain regex by using the lookahead pattern ((?!regex).)*.

Now this was a lot of theory! Let’s get some practice.

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