First clear solution for Cipher Map by Sim0000 - python coding challenges

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First solution in Clear category for Cipher Map by Sim0000

def recall_password(cipher_grille, ciphered_password):
    def rot(g):
        return [[g[3-x][y] for x in range(4)] for y in range(4)]

    password = []
    for i in range(4):
        password += [ciphered_password[y][x] for y in range(4) for x in range(4) if cipher_grille[y][x] == 'X']
        cipher_grille = rot(cipher_grille)
    return ''.join(password)

May 21, 2014

Comments:

Ross on March 31, 2017, 4:43 p.m.
I am amazed at how creative people can be. As a beginner, I did not think about creating a rotating function, or using list comprehension for multiple levels of for loops. While my code outputs the same thing, yours is much easier to follow, much cleaner, and faster. I guess coding does not come naturally, as I hoped it would. Thanks for this clear and clean code for me to learn from. Just a question, would zipping the grille and password make running the program slower or faster than running for loops to compare the two?

Sim0000 on March 31, 2017, 7:23 p.m.
Thank you for your comment. I try to measure execution time. <pre class='brush: python'>from timeit import timeit print(timeit("f(c)", setup="c = ('X...', '..X.', 'X..X', '....'); f = lambda x: list(zip(*x[::-1]))")) print(timeit("f(c)", setup="c = ('X...', '..X.', 'X..X', '....'); f = lambda g: [[g[3-x][y] for x in range(4)] for y in range(4)]")) </pre> The result is following. <pre class='brush: python'>1.2330488303683145 5.653868712069415 </pre> In my environment, zip is faster than loop :-)

Sim0000 on March 31, 2017, 7:43 p.m.
I have mistake. Correct code is following. <pre class='brush: python'>from timeit import timeit print(timeit("[c for c, g in zip(''.join(C), ''.join(G)) if g == 'X']", setup="C = ('itdf', 'gdce', 'aton', 'qrdi'); G = ('X...', '..X.', 'X..X', '....')")) print(timeit("[C[y][x] for y in range(4) for x in range(4) if G[y][x] == 'X']", setup="C = ('itdf', 'gdce', 'aton', 'qrdi'); G = ('X...', '..X.', 'X..X', '....')")) </pre> The result is <pre class='brush: python'>2.300727633312656 4.64237267926328 </pre> This result shows zip is faster than loop :-)

Ross on April 1, 2017, 1:50 p.m.
Sim, When you import timeit does it automatically time all the operations that you run? Does timeit work on Jupiter Books? Thanks for you input.

Sim0000 on April 3, 2017, 9:08 a.m.
No. timeit function have two argument as string and only time first argument. See <a href="https://docs.python.org/3/library/timeit.html">document</a> for more detail.

vinitrinh on May 26, 2017, 2:52 p.m.
Hey I got a question. in the Password List comprehension, where you add 2 ranges... how do you know it would catch the letters in the right order? Because the "for y in range(4)" comes first, doesn't it look for the letters downwards across the rows first instead of looking horizontally across the columns?? that would give the wrong solution.

Sim0000 on May 26, 2017, 3:49 p.m.
Line 7 is following <pre class='brush: python'>password += [ciphered_password[y][x] for y in range(4) for x in range(4) if cipher_grille[y][x] == 'X'] </pre> This is equivalent to <pre class='brush: python'>for y in range(4): for x in range(4): if cipher_grille[y][x] == 'X': password += ciphered_password[y][x] </pre> I don't really understand your question. Is this the answer what you want?

vinitrinh on May 30, 2017, 3:37 a.m.
Ohhhh thanks heaps for your reply. I totally got it now. It loops through the x first, then loops through the y.

abehad701 on June 6, 2017, 5:13 p.m.
Nice function for rotation! very creative.

kuzdras on June 28, 2018, 2:11 p.m.
Very nice and clear function(s). My first thoughts were: 'So that's how I can put 4 lines of my code into one'. Really educational.

Splitter on Aug. 4, 2019, 5:14 p.m.
Well done, but are you sure about positions of `x` and `y`? I mean `[g[3-x][y]` and `ciphered_password[y][x]`. Do `x` and `y` mean a row and a column, or they mean x and y axes?

t4d3uszk on Sept. 5, 2019, 9:53 a.m.
And I am rotating grill writing all sums by hand instead of using such simple function :( It is a difference between a newbie and an experienced programmer.

kdim on Jan. 28, 2021, 4:34 p.m.
good work!

List, list and list again

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