First clear solution for Boolean Algebra by Sim0000 - python coding challenges

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First solution in Clear category for Boolean Algebra by Sim0000

def boolean(x, y, operation):
    if operation == "conjunction": return x & y
    if operation == "disjunction": return x | y
    if operation == "implication": return (1 ^ x) | y
    if operation == "exclusive":   return x ^ y
    if operation == "equivalence": return x ^ y ^ 1
    return 0


if __name__ == '__main__':
    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert boolean(1, 0, "conjunction") == 0, "and"
    assert boolean(1, 0, "disjunction") == 1, "or"
    assert boolean(1, 1, "implication") == 1, "material"
    assert boolean(0, 1, "exclusive") == 1, "xor"
    assert boolean(0, 1, "equivalence") == 0, "same?"

Sept. 3, 2014

Comments:

artemrudenko on Sept. 3, 2014, 5:48 p.m.
ifs))) each and every time i am seeing a lot of ifs i wonder about switch...case. Unfortunatelly in python we have only dicts to somehow cover switch..case functionality. In any case thumbs up)))))

Sim0000 on Sept. 5, 2014, 11:52 a.m.
Maybe dictionary solution is more pythonic :-)

artemrudenko on Sept. 6, 2014, 9:10 a.m.
stackoverflow pythonistas are using dicts, ans since i have learned python from their answers i am always using dicts as well(and for this task too). however i don't feel any problem with those who are using ifs))))

aotus on Sept. 6, 2014, 6:51 a.m.
See my solution... I used a dictionary! And lambdas, which I ordinarily dislike!

mu_py on Oct. 22, 2022, 10:06 p.m.
It took a while, but now our dreams came true: <a href="https://docs.python.org/3/tutorial/controlflow.html?highlight=match%20case">https://docs.python.org/3/tutorial/controlflow.html?highlight=match%20case</a>#tut-match

Cjkjvfnby on Sept. 4, 2014, 7:10 a.m.
line 7 will never be executed

Sim0000 on Sept. 5, 2014, 11:51 a.m.
Yes. I think I should raise exception.

maurice.makaay on Nov. 3, 2014, 7:25 a.m.
Yes, I agree on that. Line 7 will be executed, in case the operation is incorrect. If this were a library that was used in production, typos in the operation name would lead to weird bugs in the calling code. Errors should never be hidden like this. A dictionary solution fixes this automatically, since a KeyError would be raised when using a non-existing operation. For this implementation, I would recommend replacing line 7 with a line that raises an exception instead.

taras-sereda on Sept. 4, 2014, 5:55 p.m.
For understanding. Is it more efficient to have several IFs instead of one IF with a bunch of ELIFs?

Sim0000 on Sept. 5, 2014, 11:50 a.m.
In general, if ... elif ... is more efficient than ifs. Because ifs execute extra compares. By the way, in this case if ... elif is same performance as ifs. Because if ... return execute no extra compares.

xtofl on Sept. 8, 2014, 5:49 p.m.
Unknown operations return zero in this implementation - It's more correct to raise an error (KeyError would be ok).

Sim0000 on Sept. 9, 2014, 7:49 a.m.
Thank you for good advise. :-)

MarkVickers on Oct. 4, 2014, 1:34 a.m.
Are there any online sources that would make this problem, including the use of the operators in this code, more understandable to a beginner? I solved this in a rather seat-of-the-pants manner because I couldn't find a good online explication. I didn't find the cited Wikipedia page very helpful. Even now, I'm trying to grasp phrases such as x ^ y ^ 1. My solution used painfully primitive phrases such as, in this case, "(y is x)".

Sim0000 on Oct. 4, 2014, 5:07 a.m.
Thank you for your comment. You may read about <a href="http://en.wikipedia.org/wiki/Logical_conjunction">logical conjunction</a> in wikipedia. x != y is equivalent to x ^ y. Not x is equivalent to x ^ 1. So, we can get x ^ y ^ 1 = (x ^ y) ^ 1 = not (x != y) = x == y. In this case, 'x == y' is better than 'y is x' as x equivalent to y. 'x is y' means test both x and y are the same object. It is stronger operation and careful to use. Have a nice coding. :-)

MarkVickers on Oct. 6, 2014, 1:42 a.m.
Thanks very much

MarkVickers on Oct. 4, 2014, 3:33 p.m.
Thanks very much. So I could wrap my head around it, I've written the following. If you can, please let me know where I have things wrong: Conjunction means the addition of two statements together (e.g., “x & y”, or “x and y”). If either of the statements of False, the outcome of False. If both statements are False, the outcome is False. The outcome is True only if both statements are True. Therefore, True and True is True, but True and False is False. Disjunction means the selection of one statement over the other (e.g., “x or y”, or “x | y”). As long as True is an option, the outcome is going to be True. Therefore, True or True is True, and True or False is True, but False or False has to be False. Implication means that a statement is either greater than or equal to another statement, e.g., “x <=y”, or “(1 ^ x) | y”. Therefore, the statement that California is either greater than or equal to the Golden State is True. The statement that California is either greater than or equal to San Francisco is also True. But the statement that San Francisco is greater than California is False. (I should probably use numbers there, but this is more fun.) Exclusive means that both statements are exclusive to one another (e.g., “x != y”, or “x ^ y”. They are not equal. Therefore, the statement that a dog is not equal to a cat is True, but a statement that a dog is not equal to a dog is False. Equivalence means that two statements are, well, equivalent (e.g., “x == y”, or “x ^ y ^ 1”). Therefore, the statement True == True is True, and the statement False == False is True, but the statement that False == True is False.

Pyth0n2 on Jan. 8, 2015, 5:47 a.m.
Thats... so clean.

l2032 on Jan. 10, 2015, 12:41 p.m.
the exclusive operation seems wrong. The question states that the if x=0 and y=0, the return should be 0. However, 0^0 = 1?

l2032 on Jan. 10, 2015, 12:43 p.m.
Nevermind, coming from R, I misinterpreted ^ as an exponent.

iggymas on July 7, 2015, 10:05 a.m.
Nice!

maksimkovnir on Jan. 11, 2016, 6:39 a.m.
Clear! I haven't thought about Boolean Signs (& and other). thx)

BillDoors on April 6, 2016, 5:26 p.m.
I'm searching for this operators. Can you share where did you learn this logical operators? Thank you!

Sim0000 on April 7, 2016, 12:57 a.m.
I learned a logic circuit to a college student in Japan.

BillDoors on April 7, 2016, 3:10 a.m.
Wow!Where are you from? Studying abroad is a cool stuff.

BillDoors on April 7, 2016, 3:11 a.m.
Okay. Now I learned it from you.

AudreyJean on May 27, 2016, 5:49 a.m.
I did not recall ever seeing these operators before, but I found them <a href="https://docs.python.org/3.1/library/stdtypes.html">here</a>. Thanks for an interesting solution.

Thenbacker on Oct. 6, 2016, 4:13 p.m.
Nice use of the operators!

chchun on Sept. 23, 2018, 10:25 p.m.
good!!!

1wow.dow1 on Dec. 25, 2021, 10:45 a.m.
let me learn new

lxf42 on March 25, 2022, 8:56 a.m.
The solution didn't age well, in the meantime we have the match-case statement in python 3.10

Look up in the Dict()

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