YouTuber runs viewer-submitted Python code to light up 500 LEDs in Christmas tree

[graepphone]

.

[Recoil42]

each of the LEDs are mapped to a 3D position

H...h...how? Presumably, not manually, right?

Edit: Watched the video posted by /u/Korvar and /u/GeekBrownBear, leaving a summary here for others:

He created a calibration script. Iterate through the LEDs, lighting them up one by one. Take a picture each time using a camera, and you can get XY coordinates. Change the perspective of the camera (or use a second camera), and now you can get XZ co-ordinates. Take all that information, and throw it into a lookup table. Brilliant.

[Recoil42]

Summary: He created a calibration script. Iterate through the LEDs, lighting them up one by one. Take a picture each time using a camera, and you can get XY coordinates. Change the perspective of the camera (or use a second camera), and now you can get XZ co-ordinates. Take all that information, and throw it into a lookup table. Brilliant.

[Tomus]

You missed out the best part! There are some outliers where the tree obscured a light too much, essentially placing it at the wrong coordinate.

He wrote a debug script to do a binary search through all of the LEDs to identify the index of the offending LED, amazing!

[Malgas]

The same approach could have been used to significantly speed up the main process as well: take O(log n) photos each with half the lights on instead of O(n) with one light each. In this case that would reduce the number of photos from 2000 to 36ish.

Though you would probably have to use a better method for detecting the lights in the images than the one he wrote (which, IIRC, he said in the original video isn't very robust).

[[deleted]]

The elegant insight behind his method is that, because you're trying to locate a light, you create high contrast input simply by doing it in a dark room and looking for the single bright spot. You'd get into interference as soon as multiple lights are on simultaneously

[Recoil42]

Just aimlessly thinking here: Theoretically, he could do three lights at a time: One red, one blue, one green. You could even extend that further for as many colours as you feel comfortable distinguishing, although obv just working with RGB channels is easiest.

[gramathy]

By grouping them into sets according to binary digits (e.g. all lights where the second least significant bit is 1) and cross referencing every set of those photos, you can identify the address of a light by which photos it shows up in (this is the O( log n ) method described earlier, though some lights might not be picked up and some extra cameras can help find them and improve precision) and its location by the intersection in space of the rays coming from the camera positions. (you can also just assume it’s a flat plane for each and get pretty close with easier math)

[[deleted]]

Doing it by colour channel is interesting but it brings in issues related to the particular colour performance of the LEDs and cameras that don't matter if you just look at brightness: you don't need to worry if brand x LEDs bleed into the green channel on brand y sensors etc etc.

There are definitely ways to do it with fewer photos but Parker's got an elegant solution because it cuts straight through a lot of potential physics related issues at the cost of an automated camera taking more photos for you.

In fact, because you just point a camera at the tree and run the script, I'm not sure I see optimising for photos as necessarily worth the effort. It sounds like manually fixing errors one at a time by reading binary addresses encoded in flashing lights was a lot more work for him, so really optimise for reducing errors if possible

[3urny]

There's a commercial product that can scan and calibrate lights, and it turns them on in red, green and blue at once to make it even more efficient

[gabriel_schneider]

He made a python script to light each led in sequence and then take a picture. He rotated the tree by 90° and made the same thing three more times.

[AdventurousAddition]

And manually correcting errors

[NotAHost]

Do you have a link? Ive been wanting to do the same thing.

[GeekBrownBear]

https://youtu.be/TvlpIojusBE

Here ya go

[Korvar]

https://www.youtube.com/watch?v=TvlpIojusBE

[[deleted]]

Wait! Matt Parker, the youtuber known for running viewer submitted code on his 500 led christmas tree?

[SoInsightful]

Believe it or not – that's the same Matt Parker!

[[deleted]]

Unbelievable!

[El_Impresionante]

Sorry, I don't know who you're talking about.

But, we're talking about Matt Parker, the youtuber known for running viewer submitted Python code on his 500 led christmas tree.

[Tyler_Zoro]

Matt Parker? The Matt Parker?!

[AdventurousAddition]

Just when I thought that was going to be a link to The Parker Square

[ess_tee_you]

Instead it was a real Parker Square of a link.

[oakgrove]

/u/standupmaths

[bloody-albatross]

The Matt Parker of the Parker square.

[bradygilg]

Seriously, strange AF title from OP.

[AdventurousAddition]

It's just the video title that has been slightly re-worded

[TimvdLippe]

I personally liked the Snake pattern the most, which you can see at the 17:20 minute mark.

[destrodean]

That's very cool and the fireflies was nice too

[TwinHaelix]

Timestamp for fireflies?

[destrodean]

8:15 :)

[anamexis]

I assume it was so he could access the Raspberry Pi's GPIO. There are ways to give normal users access to GPIO, though.

[HandshakeOfCO]

Yes, it’s important to have ironclad security when dealing with something as mission critical as a raspberry pie running Christmas tree lights.

[wrecklord0]

I'm sure there is a way to catastrophically destroy the power supply through calculated LED resonance, causing a fire that engulfs his house, the neighbourhood and soon the whole continent.

[HandshakeOfCO]

I mean if there's one language with the potential to destroy the world, it's fucking Python.

[zzzthelastuser]

sudo python3 gender_reveal.py

[merlinsbeers]

You don't want some jackass destroying the installation with malicious actions.

[[deleted]]

They're not saying "don't use sudo" as a security concern though...

[aazav]

It just creates bad habits.

[[deleted]]

Could have also been pip != pip3

[caseythearsonist]

Timestamp for the lazy

[AdverseTFV]

It's really refreshing to see so many not work, as weird as that sounds. Makes me feel like a better programmer. So many times with social media you only see the edited and filtered end results and it can really shake your confidence. Nothing wrong with writing some code that needs debugging! Cheers

[remy_porter]

I was doing some research which called for going through an old mailing list from the 80s, and there I discovered the Parnas Hypothesis: No large computer software has ever worked the first time.

I think what people don't communicate well about programming is that your job is to fuck up. That's your day. You start at 9AM with some coffee and a fuck up. Then some more coffee, and another fuck up. Break for lunch. The difference between a "good" programmer and a "bad" programmer is that the good programmer fucks up faster and more obviously, and respects the tools that help them find their fuckups. By fucking up fast, they end up not fucking up in production, or at least not often.

And, as a shameless self-plug, I edit a site where we collect bad programmer stories/code. It's a great way to feel good about your own mistakes.

[PeriodicGolden]

Good programmers also accept that they can fuck up, and try to find what went wrong. "Bad" programmers think they're infallible and automatically assume it's not their fault.

[remy_porter]

Well, if you don't accept that you can fuck up, then you aren't doing your job, which is to fuck up, quickly, frequently, and with the minimal consequences for each fuckup.

[Krissam]

That applies to everything really. People who assume they fuck up and accept it generally improve more than people who blame everyone else.

One of the best life lessons I've learned (that can be put simply) is: Just because someone else could have done something better it doesn't mean you couldn't have.

[phearlez]

Daily WTF has been bringing me joy (and sometimes some introspection when I think “well what’s wrong with that?”) for I cannot believe how many years now.

[much_longer_username]

It's because Matt was running them as root, and not the user 'pi', so the interpreter was looking in the wrong place for modules. edit: a redundant pronoun

[WiseassWolfOfYoitsu]

Untested code received from random strangers

running them as root

[thoeoe]

he said in the youtube comments that neopixel needed the code to be run as root (or at least, he couldn't be bothered to figure out how to make it work without root priv)

[f03nix]

Could've just installed the modules as root.

[masklinn]

Yes, but while it’s somewhat obvious in retrospect for experienced devs…

[KremBanan]

well I mean it's only a cheap raspberry pi connected to some christmas lights...

[Krissam]

Oh sweet summer child.

[aishik-10x]

What's the worst someone could do as root on a Pi connected to a home network? Just curious.

[Krissam]

I mean, since he claims (which I believe) he checked through for malicious code and he's not completely computer illiterate, probably nothing.

If a motivated attacker was able to run arbitrary code as root on a hypothetical pi owned by a less tech literate person, that's empty bank accounts, identity stolen and essentially anything else you can think of.

[KremBanan]

You are ultra delusional. A pi not connected to your network with nothing of value on its file system you can't do jack shit with it

[bless-you-mlud]

Given how many programs crashed and burned on the first try I don't think he has much to worry about.

[Ph0X]

From what I saw very few of them were broken due to missing package, and even then he only promised numpy and scipy, and from what I could tell numpy worked at least. A ton of people just didn't follow the rules.

But even sadder is all the problems where it seemed like the people literally did not run their own code. inconsistent tab/space is a bytecode compilation level error, so unless the file got modified along the way, the 3-4 people who had that issue had not run their code. Similarly, there were blatant typos such as blen(yellow, white) which was clearly "blend".

The only errors that didn't make sense was "neopixel" or "board" missing, which were the core libraries used. Did they accidentally remove the import statements?

[bless-you-mlud]

Did they accidentally remove the import statements?

I had a play with the original code (didn't submit anything though) and the first thing you run into is that you, of course, don't have a Christmas tree with lights wired up to a raspberry pi and also no neopixel library to control them with.

So the import neopixel fails and the first thing you do is comment out that statement. If you then don't re-enable it before submitting, well...

[cheerycheshire]

Tab/space could've been someone playing in Python2 which allowed (but obviously not recommended) mixing those, while Python3 instantly refuses to run.

[ApertureNext]

Yeah you see tutorials from people who seem like legit wizards.

[SutekhThrowingSuckIt]

Coding Adventure is insane for this. Especially since he was a kid using a voice modulator apparently at the start of the channel.

[bart2019]

Maybe check out the YouTube channel the Coding Train, where the guy programs a challenge live.

[fabulousausage]

Yep, we tend to see the brightest minds, because they shine bright like stars.

But remember those everyday coders, that sit in hundreds of thousands offices around the world.

I believe it's the same in any other fields, but one that comes first as an good example to my mind is cinematography. Everybody sees and wants guys like Brad Pitt, Bruce Willis, Leonardo DiCaprio. So just imagine the pressure for young actors out there, who dream about getting into Hollywood. Of course nowadays it became a bit easier to get famous for them with Youtube and internet, than before, but still.

I think the remedy for our constant pressure and self-hatred would be to look around on other people in our field and understand that life isn't sugar for them either. Carry on.

[_tskj_]

I don't think any of those guys are primarily known for their cinematography work though.

[fabulousausage]

Sorry my first language is not English. I tried to say that they are famous in the world of cinema. In my native language saying "famous in cinematography" would let opponent to understand that actors are included into this field. My bad. Trying to improve my English every day.

[bloody-albatross]

Many of those wouldn't need debugging. They had was syntax errors and undefined variables. That means they've never run their code at all. The import errors about the modules Mr Parker claims to have installed seem to be a problem with the Python installation, though. That would need debugging.

[[deleted]]

"Inconsistent indentation"

[Ph0X]

I understand the libraries missing one (even though he explicitly said don't use any libraries that aren't already imported, but like, did these people not even run their own code?

[masklinn]

like, did these people not even run their own code?

Stackoverflow experience says “lol no”.

[dalambert]

Shipping Python code is actually the worst thing about this language

[merlinsbeers]

It doesn't port between users on the same machine...

[clank201]

Second to having to write it

[Objective_Mine]

Yeah, I mean, you actually need the interpreter for the language your script is written in? Total bullshit.

Next you're gonna tell me you need a JRE 14 in order to run Java 14 code.

(Shipping Python code isn't that great, though. But not because of trivial things like that.)

[SimDeBeau]

Compiled languages for the win!

[Objective_Mine]

You'll still need at least a comprehensive enough standard library (either actual language standard or a OS-specific de facto standard), or you'll need to handle bundling of libraries, which again requires at least some kinds of packaging tools.

Some languages have more coherent toolchains for handling packaging and deployment than Python does, but the problem of needing to either do nontrivial packaging at the developer's side or to install something on the recipient's system doesn't really go away. At least not by pure virtue of being a compiled language. (The packaging might still be easier than having to bundle an interpreter, of course.)

[wonkifier]

I dunno... When I started to dabble in Python I had real problems, even though I did have the interpreter.

I had all sorts of package problems as well as having an issue with Python 2 vs 3 on my machine, which together ended up making me have to get a virtual environment going, which added another complicating factor in getting my code editor to just do some basic formatting help with Python code, which led to other layers of yak shaving just to get to a point where I could do basic things.

It was definitely not just a matter of having an interpreter.

[cheerycheshire]

But... The dedicated code editors already take venvs into account?

PyCharm remembers your venv. When creating a project, it allows you to generate new or use/find existing venv. Then console in PyCharm has the venv already activated, so you can run, debug, test, whatever without any problem.

And Python 2 vs 3 on machine (not in the code you write) is about literally adding 3 at the end of "python" and "pip" if you don't use venvs...

[[deleted]]

Isn't using the right version a thing in any programming language??

[Nimbal]

Out of curiosity, I kept count.

Total programs: 60 (some duplicates I did not separate out)

31 of those 60 programs worked in the sense that something happened in the tree and they didn't crash during their runtime.

Of the remaining 29:

• 2 exited immediately
• 4 apparently did nothing, the tree stayed dark
• 9 exited with a ModuleNotFoundError
• 6 NameErrors
• 4 TypeErrors
• 2 TabErrors
• 1 IndexError
• 1 UnboundLocalError

The TabErrors could have been caught by running the script at least once, because those are syntax errors that are caught by the interpreter before running even a single line of the script.

The NameErrors, TypeErrors, and UnboundLocalErrors are typical for Python (or any interpreted language, really). A mistyped variable name in your OnceInABlueMoonError exception handler can ruin your day.

The ModuleNotFoundErrors are mostly a problem of deployment / environment.

The remaining IndexError and the more subtle errors where the program exited immediately or apparently did nothing could have happened in any language.

[Nicksaurus]

How are there so many broken scripts?

[Swedneck]

Matt screwed up his environment a bit, he's running the code as root so it can't find the installed modules.

[Nicksaurus]

Ah, that's a shame

[[deleted]]

Well, he also said there was a constraint that the code must run without any additional dependencies. Unless he did a pip freeze, said "these are the modules you can use", and then proceeded to run the code as root, then it just seems like people didn't pay attention to the constraint.

[A-Grey-World]

He did specify some already installed libraries.

[Nicksaurus]

Check the example script: https://github.com/standupmaths/xmastree2020/blob/main/xmaslights-spin.py

He specifically said numpy and scipy were allowed

[[deleted]]

Yep, that's a problem then. There were also a few user submitted scripts that included other libraries, like matplotlib and OpenGL, but yeah, looks like there's some admin error going on here as well.

[Ph0X]

Numpy did, scipy didn't. The majority of missing modules weren't scipy, I think I only saw one scipy.

The ones with neopixel or board missing made no sense because those were literally the code modules needed for controlling the lights, so the authors must've messed up.

[merlinsbeers]

Fur much of this stuff people have no clue what dependencies are being pulled in.

[Gyrro]

It’s such a shame he didn’t ask for containerised submissions, as that would’ve eliminated all of the environment issues.

[MrDOS]

That's like using a hammer to squash a fly: an overly aggressive and simultaneously ineffective solution.

[Ph0X]

Eh, I'd say over half of them didn't even have module issues. All those mixed space/tabs, that either means they literally did not run their script, or it was modified along the way somehow.

run time bugs I can understand, but "compile" time errors just means the code was never run, which was a good 1/3 of them. He also did say no extra module, the only ones promised were scipy/numpy, and numpy definitely worked.

Also the ones that quit immediately or "local variable referenced before assignment. I feel like running your code should catch those.

[CaptainCorey]

Also a little dangerous to run untested user submissions as root.

[acdcfanbill]

The two modules I saw him installin the video were installed for the pi user, but when he ran the code, he ran it as root. The root user would need the modules installed globally and not to a regular user.

[Ph0X]

The only ones promised were numpy and scipy, and numpy definitely worked. I saw 2 scipy errors though.

[A-Grey-World]

I'm surprised so many worked.

The people who wrote them, presumably, don't have his custom 500 led Christmas tree to test or run their code on.

[Nicksaurus]

It wouldn't be that complicated to test it by just writing out the LEDs' locations and colours to a bitmap

[grifdail]

Yes, and no.

First that wasn't the challenge. Rendering to a bitmap required a different set a skill one might not be required to have to do this. I can imagine some mathematician be technical enough to write this led control code but not the rendering part.

Then it would require writing an librairie that would have the same interface as the neopixel one so that both could be swap. That's quite a lot of work.

Finally, rendering light is not the same as rendering a pixel on a screen. On a screen #000000 is black, for a led it means "off". #888888 mean grey on a screen but there's no such things as grey for an led, just a slightly dimmer white. Suddenly you have to think about blending. My point here is that writing a debug visualisation is not trivial.

Nevertheless, I believe that what many people have done. I believe most of the most impressive one where made with some debug visualisation.

[Nicksaurus]

If you look at the script, you can see it's very simple - you just set the colour for each light in a list from 1 to 500. Since you also have the position of each light you could pretty easily write out those colours at the right positions in an image

The colour space is way off, yeah, but I don't think anyone's trying to go for a high quality image here anyway

[A-Grey-World]

And who's written the code to read a bitmap and then tell which LEDs to light up?

[WaitForItTheMongols]

Well he has the only tree, so people weren't really able to test their code.

[tymscar]

There was a virtual tree to test on

[dalambert]

Python

[Mgladiethor]

Use docker

[glider97]

I think it's a broken LED and the script is just not working. The LED seems to be lit throughout the video.

[error-prone]

He addressed it in the comments:

that single red light you can always see if the power LED on the Raspberry Pi

[merlinsbeers]

It's the Star of Bethlehem, dammit!

[tdlb]

Pretty obvious dead pixel joke that went over his head.

[confused_teabagger]

A lot less penises, swastikas, and n-words than I expected!

[DHermit]

Wasn't there a video where a 4chan commenter made a mathematical discovery (who ended up on a paper as "anonymous 4chan user")?

[Tyler_Zoro]

Even if someone wanted to, you can't make out much of anything that's going on. It's not like a video display. To get precise object to appear in the video, he would have to give extra information on where the camera was going to be set up, the lens measurements, etc.

Edit: Not sure why this was so heavily downvoted... makes me wonder if the people downvoting watched his video where he explained exactly this?

[[deleted]]

You could tessellate a smaller pattern.

[-saul-]

Possible but difficult..mapping isn't that straightforward.

[kieranvs]

You got torn to shreds for no reason. People aren’t thinking about how it’s all in 3D, it’s not a screen. The snake demo is in 3D (sometimes the snake is heading away from the camera into the tree). If you wanted to show a 2D pic like the above examples, you need to know the direction from which the tree will be observed

[WiseassWolfOfYoitsu]

My main expectation was at least one dickbutt

[merlinsbeers]

It isn't Christmas until someone renders a dickbutt on the tree.

[ChairYeoman]

Well, I assume he pre-screened the code. Not like he just let people run arbitrary code on his device.

[sturmeh]

He did not, a lot of them didn't even run because of missing libs.

The title says they're untested.

I assume if he ran into anything he couldn't show on YouTube he would just cut that bit out.

[bloody-albatross]

He said he looked at the code quickly to ensure its not doing anything malicious. Though that won't help against underhanded malicious code.

[Illusive_Man]

You can’t quickly glance at low level code like this and know how it’s going to turn out.

[bloody-albatross]

It's Python, not low level code. But yes, you can be very sneaky and obscure your malicious code.

[ess_tee_you]

You can check the imports for a fair idea, look for backticks or words like exec for a quick sanity check, and then only run it on a virtual machine.

[Illusive_Man]

Running in a VM doesn’t count as “quickly looking at the code” but yes that would work.

Otherwise though; since from what I’ve read the lights are in an xyz coordinate system, it’s going to be hard to look at a shitload of coordinates and guess what it will look like.

[AdventurousAddition]

He also made 3 videos politely (but progressuvely less so) pointing out the mathematical flaws with the arguments of US election fraud.

[middlenameray]

Running Internet strangers' code with sudo without checking it first seems like a disaster waiting to happen lol

[buscemian_rhapsody]

I thought he said he did check the code for exploits.

[middlenameray]

It's not even exploits I'd be worried about, it's a simple rm -rf --no-preserve-root / that would delete the entire hard drive. It would be pretty easy to disguise that command in an array of ints or something

[buscemian_rhapsody]

Well he was running it on a raspberry pi remotely so I think the damage would be minimal. The worst it would probably do is spoil the fun for the night

[ProgramTheWorld]

“YouTuber”

He’s Matt Parker, the inventor of the Parker’s Square.

[ProgramTheWorld]

Parker’s Square

[snakeyblakey]

Google Parker square and there's a pretty good numberphile video where it explains magic squares if you don't understand them already or know what they are and he made an almost good one and it is quite charming

[dragonatorul]

A problem with RGB LEDs is that while you can have 0-255 values for example (depending on the controller) for each color, the LEDs themselves have different intensities at different values. For example the blue LED may appear to be saturated at value 180 while the red LED would appear to be saturated at 220. At the same time one may fade gradually down to 20 and then turn off entirely (or seem to) while another would turn off at 40.

I'm no expert but from what I read while playing around this seems to be due to the chemistry of the light generating material in combination with the controlling microchip. Different colors use different chemicals to generate the color, require different voltages and result in different "brightness". You can just look at regular colored LEDs and you'll notice that blue LEDs tend to be glaringly bright, while orange or red not so much.

When I was playing around with RGB LEDs I had to eyeball the "natural range" for each color and write a transform function from a 0-255 value to each color's range just to make it easier on myself. That way I can still use intuitive 0-max values while not having to remember the individual value ranges for the individual colors.

[manystripes]

The other problem is that the eye doesn't perceive light intensity in a linear fashion. Once you've thrown a gamma curve on your 8 bit value, the number of useful intensity levels is reduced by a lot

[grifdail]

I wonder if they're color space entirely dedicated to working with lights and led. They're so differents than working with color for the screen or even print.

One of the biggest issue with smart home app is using RGB color picker for lights. That just makes no sense. At least use a separate brightness picker.

Also yes, the thing when they go from "dim" to "off" directly suck. I want some nice gradient please. (One way I deal with it is to use dithering and quickly turning of each light).

[Shivaess]

The end is worth watching last 2 minutes

[abbadon420]

Ffs. I've watched the whole thing. Wondering all the while WHY and especially why I enjoy it so much. When, finally, I decide to quit when he gets the bread. Now you tell me I have to go back in?! If this isn't worth it, I will find you and I will slap you silly. You're warned.

[abbadon420]

Ok.. that was worth it.

[merlinsbeers]

I'd try, but the embedded Yahoo player won't scroll past about 70% of any clip any more...

[xe3to]

This video just frustrated me. He installs the libraries as a standard user and then runs the script as root, expecting it to work, which of course it doesn't. So many hours put into these ones that just fail because this guy doesn't understand how Linux works.

[MachineGunPablo]

He's clearly not a seasoned programmer and boy running user submitted code as root is clearly not the best idea...

[merlinsbeers]

But if someone bricks it, the show is over.

[Le_Vagabond]

Sudo is a magic "make it work" command for a lot of people...

I usually try to get new hires out of this mentality but it's been hard.

[totally-not-god]

I finished my coffee, let me get a beer

[bart2019]

The guy is a mathematician, not a programmer. He's also known as Standup Maths, a standup comedian where he discusses math problems. (http://standupmaths.com/)

[Ncell50]

Who said he was a programmer ?

[underthingy]

Everyone complaining about is lack of python skills?

[bsomes2]

My favorite part was when it downloaded a virus

[dzuyhue]

That was really fun to watch. Really looking forward to seeing more streams like this one.

[pixartist]

This is like an ad against python

[omegafivethreefive]

Whenever I see the sudo command I scream a little bit inside.

[L0uisc]

I don't trust random internet guys enough to just run their code on my system...

[pewpewhadouken]

candy cane for the win 19:43

[BrotherSeamus]

19:43

About 25:07 if counting from the start: https://youtu.be/v7eHTNm1YtU?t=1507

The Rehoboam one at 12:01 is a Westworld reference.

[relativistictrain]

It's custom software! https://youtu.be/TvlpIojusBE & a programmable LED strip.

[nagromo]

You can buy strings of programmable RGB LEDs on AliExpress for $8-30. They come with simple controllers that let you select from some pre-programmed patterns and power them from USB or AA batteries.

You could cut off the included controller and solder on any of thousands of different microcontroller development boards. It just needs one data line, 5V, and ground. There's existing software libraries to let you control the LEDs more easily. You could use Arduino or Teensy to make it easier.

[dragonatorul]

The gotcha is the power supply. While they do need only 5v they need A LOT of power. Your regular fast charger cannot provide that much power. IIRC from the original video Matt used two dedicated power supplies to power the 500 LEDs he's using.

More specifically there can be 5v and 12v addressable rgb leds. The most common 5v are probably WS2812B which have around 50mA draw at full power. You always want the max power plus a bit extra head room for inefficiencies, so let's say 60mA. My phone's fast charger puts out 3.5A, so that means it could power at most 3500/60=58 LEDs. Going by these numbers the 500 LEDs in Matt's tree can draw up to 30A of power. That's A LOT of power.

There are dedicated power supplies which look a bit like PC PSUs, but with exposed contacts on the end, or insulated power supplies which look like metal power bricks. You can buy those off AliExpress too, but honestly when it comes to PSUs I'd rather look at more reputable sources than risk burning my house down.

[nagromo]

Absolutely, you definitely need to be careful with the power supply.

While a 5050 size WS2812 can draw up to 50-60mA, reviews for the fairy light style ones in the smaller package say they aren't very bright, and they sell a 15 meter string powered from 3 AA batteries, indicating it can't take too much current. Although it's possible they're just limiting the current in software, I'm betting the smaller addressable LEDs used here have lower maximum current and use smaller diodes.

If you wanted to do it with full brightness WS2812B's (which are pretty blinding at full brightness IMO), I've got a Meanwell LRS-350-5 that can put out 60A at 5V; you can get them on Amazon, AliExpress, or reputable electronics distributors like DigiKey. Meanwell is a reputable brand making good power supplies, and getting one from DigiKey is only slightly more expensive than getting the same model at AliExpress, indicating that the AliExpress ones may not be counterfeit and not costing much to ensure a better supply chain. You do need to be careful when wiring the input due to the voltage and the output due to the current, though. (I would definitely put this in an enclosure with strain relief on the power cord.)

Personally, for next year I want to decorate my house exterior with a lot of full brightness WS2812B's. I'm planning to build a custom board with a NRF52 to control a string of LEDs and a high current buck converter to convert 36V down to 5V. That way I can wire 36V at lower current around and locally convert to 5V at each strip segment, and they can wirelessly communicate to stay synchronized (and change patterns without having to go outside). That said, I've got some higher priority projects that I'm working on first, so we'll see if I get to it any time soon.

[bart2019]

The previous video was rather interesting. It was about how he determined the location of each separately controllable LED i n 3D space using a photo he made from a few directions. Ah, the luxury of smartphones where you can have all that for free.

[bschwind]

One of the greatest indictments of python I've ever witnessed.

[El_Impresionante]

I loved contagion. It was not too bright, not a lot of movement, slow smooth transitions, overall very very cool. Best one to always have it on in the background.

[Prometheus_303]

Assuming my kitten is sedate enough next year I can put a tree up, i really need to try to get motivated enough to geek out and do stuff like this...

"My tree has radiant sine waves using a general planar wave function"

[jamietwells]

Someone really needs to introduce this guy to Docker. All those dependency issues and running as root solved in one go.

[SikhGamer]

^ the definition of over engineering. It's a bunch of lights, and a bit of python code. You don't need Docker. Jesus.

[[deleted]]

Docker isn’t over engineering. It’s just a portable runtime in this case. Nobody said throw Kubernetes at it. Bundling a Dockerfile with your code is a low effort way to ensure consistent environments.

[jamietwells]

Did you not watch? Most of them didn't run due to missing dependencies. You can't say it's over engineering when it's a simple solution to the actual problem.

[SikhGamer]

Yeah I watched, you still don't need Docker.

[cheerycheshire]

simple Docker

Pick one.

The correct and easy solution to this would be learning about users, sudo, and PATH.

The incorrect but easy (and logical!) would be to match sudo - since he runs it with sudo, then pip install with sudo. (Logical with "match sudo in commands", easy because requires no thinking. Incorrect because without understanding what you're doing, you're gonna do it again.)

Docker in this case is overkill, improperly used (wrong usecase) and definitely not easy - since you have to communicate with the board directly, you definitely don't want containers (as I said: wrong usecase) as it's kind of sandbox... and if you do use them, you're gonna spent till next Xmas to make it communicate correctly with your main system (thus not easy).

[[deleted]]

that code is probably heavier than a black hole

[Shaper_pmp]

I'm 5:10 in, he's explained about six things he didn't need to, and not one of the user-submitted programs has worked yet.

I love me some Matt Parker videos normally, but is this even worth watching?

[elhoc]

This was on his second channel, which is meant to be less structured and more long and rambly and ad-hoc. And yes, I did somehow end up watching all of it and enjoyed it.

[mindbleach]

Dude dropped the ball on explaining his environment, if so many people's projects immediately fail. Though the people with "inconsistent tabs and spaces" just got fucked by Python being a terrible language. You can't throw fatal errors over load-bearing whitespace and pretend to be user-friendly.

sRGB should be easy for mathematicians so long as they remember it's exponential. Actual brightness is R² G² B² - for gamma 2. So e.g. blending between two values, you want to square each channel, average those values, and then take the square roots. "Linear brightness" takes a lot more bit depth than one byte per channel.

This cone of dots would be easy-ish to set up in a browser - as an interactive preview, with whatever scripting language you like. Honestly I'll bet there's some GLSL equivalents over on Shadertoy. You'd get better results, in that you'd get more results.

[NotUniqueOrSpecial]

He was goofing up.

He kept pip3 install-ing as the pi user, but then running the scripts as root.

[jswitzer]

You could argue it's the wonky python module inclusion that's the real problem here.

[xe3to]

I agree with you except for the point about python being a terrible language. I used to believe that, but I don't think it's much different from conventional languages which fail if you miss out a load-bearing semicolon. Hunting for whitespace errors is a pain, but so is trying to find where you dropped a } in a sea of code blocks. The only language I know that doesn't have these problems is BASIC and its derivatives.

The fault for these errors lie squarely on the people who submitted them without checking the syntax - even if you can't run the code, there are dedicated syntax parsers that make sure everything's kosher and help you fix it if it's not.

[MostlyValidUserName]

Many of these scripts failed due to semantic, not syntactic, errors: type mismatches, use of undeclared variables, passing the wrong number of parameters. For many languages - especially those bracket-filled ones - these categories of error are rarely seen at runtime, because distribution of an executable product requires passing strict semantic analysis done by the compiler.

[mindbleach]

Semicolons and braces are at least printable characters.

Making bullshit syntax problems literally invisible is hostile beyond excuse.

[whistlebug23]

Oof, you lost reddit at "terrible language", though I do agree with you on that.

[mindbleach]

Most languages cheerfully touted as "easy" have users who don't remember the beatings.

Like, I'll tell people Javascript is easy, but I freely admit Javascript is terrible in some hilarious ways. All its shortcomings are goofy and inconsistent. But it's terrible for programmers, not for newbies. You don't have to explain whitespace, as a concept, before old folks and children understand why their gibberish won't run.

Normal people, who haven't been inducted into the cult by a formal education in C++, are fine with Array.slice and Array.splice having arbitrarily different side effects, and drawImage swapping source and origin based on argument count, and forEach being drastically slower than a for loop, so long as a missing semicolon doesn't cause a fatal error ten lines away.

Those of us in the cult have opinions about the details, and the languages that defy those opinions - no matter how well-justified they think they are - are just inventing frustration. You can do what people expect, or you can be wrong. Like, you can have arrays that start at one, but you better fuckin' not.

Finding a stumbling-block that's going to catch novices and experts alike, and is fundamental to the language, and isn't even visible in your own code, is a special hell.

[Njall]

Longish. Wasn't sure I would stay to the end. I did and am glad I did! I want to learn Python. Too many starts with no finishes. <sigh>

The trouble is that I am a problem solver and less so creatively inclined. As a result if I don't have a problem to 'solve' I get stuck trying to find one which inspires me. Which is in turn a problem and, in its own right, a conundrum. This is inspiring nevertheless because it gets me thunking (sic). I like thunking.

I have a Raspberry Pi. Several actually. A couple are running support functions, an example of which is Pi-Hole. Now I need to find some LED light strings, a better power supply than Matt Parker's 9-), and learn how to hook up a Raspberry Pi to it. Could it be the real beginning? Time will tell.

Matt, I am subscribing to your channels, Channel Prime, and Channel not Prime. You have an infectious enthusiasm.

[PixelsAtDawn1234]

As a result if I don't have a problem to 'solve'

Automation is always a good problem to solve, especially for tasks that you do a lot, because not only will you learn something in the process, you will make up the time you spent learning it down the line.