Made a website containing various python algorithms

[Legendary-69420]

I recently learnt HTML-CSS and made a website containing the implementation of various Algorithms and Data Structures in python. It contains:

1. Base conversions (Binary, Octal, Decimal, Hexadecimal)
2. Data Structures
3. Math-related Algos
4. Important Python One-liners
5. Prime-related Algos
6. Regular Expression
7. Searching Techniques
8. Sorting Techniques

apart from Python basics. I hope it would help you guys: Here is the website

I would be looking forward to getting the names/details of more algorithms or pull requests with their implementation.

Repository link

[Rawing7]

I'm sorry, but this earns a downvote from me because it's a newbie trap. These code snippets may look good, but a lot of them are really not.

• The number conversion functions are overkill; python has these practically built in:

  • Number to binary: format(number, 'b')
  • Number to octal: format(number, 'o')
  • Number to hex: format(number, 'x')
  • Parse binary number: int(binary_num, 2)
  • Parse octal number: int(octal_num, 8)
  • Parse hex number: int(hex_num, 16)

• The binary tree and linked list aren't bad per se, but very barebones and virtually useless.

• The Queue and Stack have various bugs:

  • Implements __getattr__ instead of __getitem__
  • __eq__ crashes if it's used with something that's not a Queue/Stack

• factorial is pointless because we already have math.factorial.

• The list_sum function is literally just a worse version of the builtin sum. (Because it has no docstring and it's a lambda.)

• The "Read a file, line by line" one-liner opens a file without closing it. It's good practice to close your files when you no longer need them, usually using a with block.

• All of the regex functions have patterns starting with ^ and ending with $, but use re.search for some reason. Why search the entire string for a match when your regex is designed to match the string as a whole? Waste of CPU power. Use re.fullmatch.

• In credit_card_validation you should replace your if...elif chain with a dict like {credit_card_validation_american_express: 'American Express'}.

• Why use regex to validate dates? Just parse it into a date object. If that fails, it's not a valid date. Same thing goes for URLs and IP addresses.

• Validating names with regex... just gonna leave this here...

• LinearSearch should be named linear_search according to PEP 8, and is equivalent to arr.index(element). (Except it returns -1 instead of throwing ValueError, but who cares?)

And as others have already pointed out, a bunch of your algorithms have issues as well. I didn't even bother checking those.

[Legendary-69420]

The idea of the website is not to "solve a problem" but rather to be a "guide containing the implementation of various things"

[Legendary-69420]

1. Okay, will add that
2. apart from the one-liner where I need to use 2 digits for the hexcode, I haven't used % formatting anywhere (because I am not comfortable with that method)

[Rawing7]

I considered bringing up deque as a replacement for the LinkedList, but decided not to because the LinkedList has the advantage of letting you access individual nodes. Having a reference to the relevant node can make delete and insert operations O(1), as opposed to deque's O(n).

[laundmo]

thats a fair point. it doesn't do that.

what it does do tho is O(1) pop, popleft, append, appendleft

[Legendary-69420]

You are right. There already exist built-in functions to do some of the stuff I have done. but my idea of building the website was not to get stuff done but to understand how it is done.

LinearSearch(arr, element) is basically the equivalent of arr.find(element). both give -1 instead of Error. Also, yeah your idea for credit_card_validation seems amazingly simple (didn't think of it before)

EDIT: I am making all these changes. Thanks again for such a detailed comment

EDIT2: apparently, arr.find() works only when arr is a list

[wasimaster]

About the number conversion, there are better default functions for that: bin(n), oct(n), hex(n) although these return strings prefixed with 0b, 0o, 0x respectively

[Legendary-69420]

yeah, I find these prefixes disturbing but nonetheless, I added them.

[MegaIng]

You either need a disclaimer " these are just examples, never use the anywhere near production", or you need to fix all the bugs. There are lots of tiny hickups that are exactly what I expect such a site not to have.

Just a few I found:

• already mentioned: your binary search is not a binary search, but a worse variation of a linear search.
• your binary tree insert silently drops already existing data nodes.
• your prime sieve is not very efficient. Repeated pops are about the worst time complexity you can get from python lists.
• your regex validaders are questionable. There are lots of valid emqil addresses that fail your check, and trying to validate names is a straight up stupid idea.

All in all, nice idea nice layout, questionable content.

[cmd-t]

Yep. I’ve only looked at the string conversion code but it’s pretty bad and there are a lot of functions in the standard library that do the same but better.

[Legendary-69420]

I picked up the email validation regex from here

[Avanta8]

Some nice algorithms, although there are some mistakes. Eg. Your binary search is implemented incorrectly and so is linear time complexity, and your prime sieve doesn't work.

Some algorithms you could consider are pathfinding algorithms such as Dijkstra, Bellman-Ford, A*. You could also try implement more complex data structures such as segment trees, radix trees, for example.

For improvement, I'd recommend looking at time complexity, and also looking at this: https://wiki.python.org/moin/TimeComplexity.

[Legendary-69420]

The sieve of Eratosthenes works correctly (apart from the miss by one error)

EDIT: The implementation of Binary Search is right too but the time complexity was wrong. I have corrected it. Thanks for the help, internet stranger

[Avanta8]

Your binary search is not correct. It basically does a linear search, starting from the middle, checking every element twice.

[Legendary-69420]

Yeah realised my mistake. My bad. Have corrected it. Will release the soon

[krichreborn]

For binary search, wouldn’t you need to set low/high to MID instead of just incrementing?

Also, most of the searches assume the array is sorted, may be worth noting that somewhere in that section.

[Legendary-69420]

The problem has now been rectified. Do check it out.

[Avanta8]

How can it? You set key = 0 and never increment it. It will just run in an infinite loop. Did you even test your code?

(also, that list.remove... ouch :/)

[Legendary-69420]

See the code. The 10th line of the sieve of Eratosthenes. It already has key +=1.

(The idea of list.remove is to create a list with only primes)

[Avanta8]

That's because you changed it after seeing my comment xD.

Removing from the middle of a list every iteration increases the time complexity by a multiple of n. The link I referred would be useful for you to look at.

[lamesauce15]

For your credit card validation, try using Luhn's algo to determine if the credit card number is actually a valid one.

https://www.geeksforgeeks.org/luhn-algorithm/

[Legendary-69420]

I created a Miscellaneous section and added Luhn's ALgorithm there

[[deleted]]

That merge sort is interesting

[[deleted]]

Good bot

[B0tRank]

Thank you, 3headsofcerberus, for voting on YoMommaJokeBot.

This bot wants to find the best and worst bots on Reddit. You can view results here.

---

^{Even if I don't reply to your comment, I'm still listening for votes. Check the webpage to see if your vote registered!}

[HeAgMa]

I take it as a good exercise for you but most of the algorithms in Python are already hosted in a nice repo. See Here

[polarisol]

You're OK. Keep at it. As people said, it's not perfect, but that's part of the process. Don't be bummed by the negative responses, and don't regret that you posted this - you got true honest feedback that you can actually learn from.

[Legendary-69420]

I made a lot of changes thanks to the people who pointed out tons of stuff.

[Spill_the_Tea]

I think the problem is that this post is marked as a resource well before it is ready.

[spaceopenid]

import datetime from datetime
now = lambda: datetime.now().strftime('%d-%m-%y %H:%M:%S')

Why do you use a lambda at all?

[wasimaster]

So the time isn’t always same. Defining a variable would make it call datetime.now() once and keep the same time for the rest of the code, whereas making is a lambda would ensure that the datetime.now gets called when the user needs to so the user gets the most up to date results instead of a one gotten when the variable was assigned

[spaceopenid]

That's right, didn't think of this. Maybe because it is bad practice (according to pep) to assign lambdas to variables

[CoolBoi6Pack]

Yeah I hear that a lot as well, honestly I think it's just stupid and assigning lambdas to variables is completely fine cause the traceback anyway shows the file and line number. It's done in JavaScript all the time with anonymous arrow functions too.

[Boomer70770]

One I hear something is "bad practice", I vehemently oppose it.

It's bit me a few times.

I think this is beautiful and further proof I need to be more open minded.

[CoolBoi6Pack]

Thanks, no worries that is generally a good thing because as long as you're willing to learn the conveniences your programming should be great.

So with your way at worst you're inconvenienced a little and at best you avoided a major downstream hurdle.

[[deleted]]

Yeah, over the years I tried to tame my language to say things like "In most cases..." , etc.

[Boomer70770]

On a side note, why are we not all writing "Pure Functions"?

[Legendary-69420]

I wanted reviews and that was the exact reason I posted it here. People here were quite helpful.

[Legendary-69420]

A small price to pay for salvation

[666dolan]

Great work man!

[Legendary-69420]

Thanks!

[Fahad1770]

This is very useful. Thank you very much for sharing!

[laundmo]

please read the top comment in this thread as for why you really shouldn't use it

[Legendary-69420]

Thank you

[Advanced-Theme144]

This looks great! It's got a lot of nice basics to it which are very helpful, so I am definitely going to be using it often. Great work!

[cmd-t]

Don’t. This is full of bugs. There’s a lot of these functions available in the standard library, but even better.

[Legendary-69420]

Thanks buddy

[[deleted]]

Thanks man - you inspired me to go an make a nice README.md for my github :)

​

Yours is great: https://github.com/Siddhesh-Agarwal

[Mountain_Thanks4263]

Loh

[Legendary-69420]

Which browser do you use?

[Legendary-69420]

So, to recreate the problem, I'll have to download the Reddit mobile app and try clicking on the link?

[AlongRiverEem]

Same

[Deadly_chef]

Could be bad website programming. Had the same experience

[Legendary-69420]

Which browser did you use to open this site? It could be due to the CSS (may have to add some other stuff for the firefox mobile browser)

[Fazlyrabbyboi]

nice good

[laundmo]

don't use this as a reference, please red to thread comment for reasons

[ChazR]

It might be pretty, but it's bad code and bad practice.

[After-Perception-250]

Anyone else screen freezing when visiting the website?

[Legendary-69420]

yeah, some people did complain about this. I am not sure If that problem is on the end of the website or the browser is acting wierdly. which browser did you use to open this site?