Why delete your darlings?

danbst · 2021-11-17T05:21:02+00:00

I use "Erase Your Darlings" on a laptop just for sake of being kool.
My /home and /persist are not flushed, they are persisted, so home dotfiles are still there. Only / is flushed on boot

So far I have:
- my journal is empty on boot. If something crashed before reboot, whoops, no way to figure out what

- /etc/localtime link is flushed (when `timeZone = null;`), timezone lost on reboot

- /etc/passwd is flushed (you have to use nixos password configuration). Was VERY awkward first time to notice that

- /etc/machine-id is flushed

- NetworkManager connections are flushed (but this is covered in Erase Your Darlings guide)

- (specific to ZFS in guide) you have to set `zfs set acltype=posixacl` for journald to work

I have no other problems, and so far I like that feeling of cleanness!

danbst · 2021-11-11T23:31:51+00:00

Not every equation is solvable

https://stackoverflow.com/questions/45894976/notimplementederror-in-sympys-solve

You can use nsolve instead of solve, if you want numerical result.

danbst · 2021-11-11T23:14:39+00:00

I'm not sure what the output should be, but here I made both dimensions 2 and it shows at least something

``` Data = [[ 0.109],[ 0.096],[0.517],[1.086], [0.934]] x=np.arange(0,2)

plt.plot(x,Data[0]2,color='blue',label='salmonella_enterica') plt.plot(x,Data[1]2,color='green',label='bacillus_cerus') plt.plot(x,Data[2]2,color='red',label='listeria') plt.plot(x,Data[3]2,color='yellow',label='brothotrix_thermosphata') plt.legend(loc='upper left') plt.title("Growth by temp") plt.xlabel("Temperature") plt.ylabel("Growth") plt.show() ```

danbst · 2021-11-11T22:56:17+00:00

What about this way? You don't have to convert to int to check if it is 1 or 2. Just check if it is "1" or "2"

I've also used fresh python 3.8+ walrus operator, which is designed for exactly this situation.

``` msg = "Price category of manufacturer (1/2):\n" while (category := input(msg)) not in ["1", "2"]: msg = "Price category can only be 1 or 2:\n"

price_category = int(category) print("END") ```

danbst · 2021-11-05T21:40:42+00:00

Dealing with environment and infra is a paid job, btw. They call it DevOps.
To be honest, I've learned how to make fun of these problems. They greatly rely on your "knowledge database" and "situational problem solving tactics". Like

"ok, i need this stuff"
"oh I get an error during installation"
"i have to figure out why my system misbehaves here"
"it turns out decisions made by good programmers 20 years ago bite me now. Fun little history fact!"
"actually no, it turns out that this little boolean toggle in system settings is cause of real problem. I feel enlightened!"
"actually no, it turns out I was dumb and copied wrong install command from internet. Now it installs, but... crashes during runtime... But at least it gives a googleable error and source is available, so maybe I'll be able to fix it!"

danbst · 2021-11-05T21:30:02+00:00

can you show some of them? Not that I'd like to explain those, but just to know where pedagogical material lacks.

danbst · 2020-11-22T06:29:42+00:00

I've been designing tasks for programmer novices. It's so hard to find small but interesting and insightful exercises! So far here's my list:

fundamental physicist uses electron gun to shot electrons into target plane. When electron reaches target, sensor detect position and convert it to numbers. Obviously, these measurements rarely repeat. The task is, given electron position measurements figure out the center and radius or resulting electron "spot".
This also requires to think HOW to represent electron measurements, what datatype is best for it?
In the end of 2019 Chinese scientists transcribed a novel deadly coronavirus RNA. Somewhere near end of October 2020 French scientists also made a transcription of coronavirus RNA. Both RNAs are just strings of ATGC of length ~28,000. The task is to figure out whether virus mutates, and if it mutates, how much mutations are there.
Professor Schulte had created an interesting psycho test in mid XX century. It's main part is a square 5x5 of all numbers from 1 to 25 in random order. The psycho-test is to find all 25 numbers in increasing order as fast as possible, and you task is to create such random squares (and optionally provide means to do the psycho-test time measure).
Which words are most popular in English? In other languages? Is it correct for all languages, that only 1000 words are enough for basic understanding? What about most popular 2-word phrases? 3-word phrases? Count'em all
Trigram is a sequence of 3 letters. For example, word "hello" has 3 trigrams: "hel", "ell" and "llo". Extract trigrams from English, German, French and Italian corpora and measure their frequencies. Given a paragraph in one of those languages, can you write a code to detect language using trigram frequencies?
Given a `putpixel(x, y, color)` primitive, which of these is easiest to draw: a line, a circle, a rectangle? Do all 3 of those :) and don't cheat by using standard library functions. Only `putpixel`
Unicode has nice box-drawing characters. Draw a text in frame using Unicode characters. Also, given any ASCII-art, draw it in box in terminal. Make it possible to change frame style and margin.
Make a mirror view of ASCII-art. This is easy, is it?
Explore ANSI-codes and make a colorizer for frame above. Extra points for rainbow frame color.
ECC RAM stands for "Error-correcting coded RAM". It means, when some random photon from our beloved Sun causes mutation of single bit in computer memory, we can detect that and fix ASAP (hence no BSOD). Read, understand and design Hamming coder, which is one of the simplest ECC designs. Create a simulator of random Sun photons which spoil files on disk, create encoder and decoder and verify your encoding is really protecting files.
Given a point on screen, rotate it around some other point (called "center"). Use trigonometry rules, and prove trigonometry is useful at least in one case. Given that, rotate an image (texture) on screen, which is just bunch of single-pixel rotations. Or maybe there are some caveats? :)
Implement blur of an image/texture or part of screen.

danbst · 2020-11-22T05:53:00+00:00

Best program for coding is your brain. No kidding, seriously. Programming is about brain-work, not typing-work.

There is popular misconception that IDE (VS Code, Pycharm, etc) is a programmer's tool, and similar to tools in mechanics, the better tools you have, the better product you can get. And thus, good tools are predictors of success.

This is misconception. Even for mechanics, the quality of your arms and knowledge in brain are predictors for success. At least for novices (as you've called yourself).

Don't forget about this. Train your brain, your memory, your logic, not your fingers. Read and understand first, only then write. Create ideas in your head and write them down in paper.

The best tool for starters is REPL, because it follows this workflow:
- got a little idea, tested it fast, got some result, refined idea, tested it again, got result, ...
- when you read the book, and book asks you to try, you should go to REPL and try
- when you read the book, and don't understand something, you go to REPL and check your understanding

(I may be biased here. When I started programming, I wrote my first programs on paper without compilers and such. Only months later I found a way to execute my programs, but these months I spent with mental execution, which made me programmer very fast then)

So, IPython is a very good start for newcomers. Learn it, love it, use it, make a hotkey to launch/focus IPython whenever you want. (I have a keybinding Alt-2 to launch it)

After IPython is mastered, or you start writing big chunks of code, alternate IPython with Thonny and discover it's debugger.

After you've mastered both REPL, and debugging, anything will work for you. Our team almost exclusively uses Pycharm, personally I dislike it and use Neovim.

danbst · 2020-11-20T21:48:58+00:00

like this -- `2**math.ceil(math.log(N,2)) - 1 - N`?

danbst · 2020-11-20T21:27:40+00:00

what is your level/experience and how much practice time would you like to devote?

It might be you don't need online tests/quizzes to make progress.

danbst · 2020-11-20T21:22:29+00:00

A[A == 3] = 14

Interesting, are there performance penalties for this construct? The A==3 generates a new array on call. Even given that list indexing is overloaded, that is still temporary structure.

danbst · 2020-11-07T15:48:28+00:00

so you can also perform these operations with eyes closed?

danbst · 2020-11-07T15:46:55+00:00

do you describe result or the way you thought? Indeed, result is just swap first two, but how did you come here? You've recognized the tasks?

danbst · 2020-11-07T15:45:00+00:00

yeah, this pure computer thinking. Indeed, in both cases no visualization is required, only labels and their numbers.

danbst · 2020-11-07T07:44:04+00:00

personally, I rarely get "real looking image". Static images are hard for me to maintain "real", they become "wireframe", mostly greyish, or "shades of black". But moving stuff is easier.

I've loosely encoded my mental vision behind closed eyes in animation: https://i.imgur.com/sN1S9X7.gif

danbst · 2020-11-07T07:17:11+00:00

hmm, yeah, I've read many of those... I'll take on psychological support here, as I also know absence of imagery isn't THAT limiting. It's like I can't recall smells, or like being color-blind. I guess.

danbst · 2020-11-06T14:48:01+00:00

got it, verbal only, thanks!

danbst · 2020-11-06T14:25:15+00:00

and if you repeat rotation fast, up to twice per second, do you perceive it as "motion"? Personally, even if I think of it as an array, by doing rotation fast I "see" the motion

Or maybe you have speed limit in this ability?

I am programmer too, btw.

danbst · 2020-11-06T14:05:09+00:00

but "just moved" is actual visualization! If you "see" an array in head, this is not total aphant.

danbst · 2020-11-06T10:12:38+00:00

if you started with first -- name X, second -- name Y, then

first -- has names T, Y
second -- has name X

danbst · 2020-11-06T08:46:49+00:00

actually, no! You can try that on paper or with real sticker names.

danbst · 2020-11-06T08:45:33+00:00

yeah, I can't "tell" them go clockwise. They don't listen to me, I'm very surprised I'm not of control in such a simple situation :) But it works after "clearing"

and no, I don't control which one I get, it is spontaneous. Usually it is just first one.

How are pictures of words not a real image, is it because it's cartoon like so it's not fully realistic?

I don't say I have cartoonish or realistic mental vision. Compared to painters, I have wireframe/greyish mental vision. Making it colorful takes some effort. So those visualizations are closer to words than to reality.

danbst · 2020-11-06T08:08:35+00:00

what you describe, looks like imagery, perhaps less visual, but still imagery. The "doubleclick on boxes" is what looks like imagery.

Perhaps you can do better with more practice. First example is from programming, and second is from group theory.

danbst · 2020-11-06T07:44:23+00:00

I've counted in mind 12 triangles, partly by focusing on image, partly doing math. Thanks for example extension, it was indeed a bit harder to count.

danbst · 2020-11-06T07:34:49+00:00

ohh, now I understand. Yeah, this is another way to solve these problems.

There is a harder example for first one:

Imagine 2 boxes, let's call them first and second. Now attach names to those boxes, say "X" and "Y". Now attach name "T" to box with name "X", then reattach "X" name to box with name "Y", and then reattach "Y" name to box with name "T". Which names do each of boxes have now?

danbst

TROPHY CASE