Second clear solution for Simple Areas by gyahun_dash - python coding challenges

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Second solution in Clear category for Simple Areas by gyahun_dash

from math import pi, sqrt

def circle(diameter):
    return (diameter / 2)**2 * pi

def rectangle(width, height):
    return width * height

def triangle(a, b, c: 'sides') -> "get area using Heron's formula":
    s = (a + b + c) / 2 # semiperimeter
    return sqrt(s * (s - a) * (s - b) * (s - c))

def simple_areas(*args):
    area_function = {1: circle, 2: rectangle, 3: triangle}[len(args)]
    return area_function(*args)

May 14, 2014

Comments:

Lijantropique on May 27, 2014, 1:29 a.m.
Hello Gyahun_dash, Do you mind explaining to me why you use "c:'sides'" in line 9? I tried your code but I always got this: <pre class='brush: python'> def triangle(a, b, c: 'sides') -> "get area using Heron's formula": ^ SyntaxError: invalid syntax </pre> Thanks a lot, Lij

bryukh on May 27, 2014, 1:49 a.m.
Did you try this in py3?

Lijantropique on May 27, 2014, 1:31 p.m.
Hello Bryukh, I use normally 2.7 and I didn't realize this code was P3 (my bad). However, this morning I tried it on <a href="http://pythontutor.com/">http://pythontutor.com/</a> and the program runs without error but I didn't notice anything additional due to this line. I will try it tonight at home with a "real' P3. regards, Lij

bryukh on May 27, 2014, 10:08 p.m.
I had tried this code in pythontutor and didn't get an error.

Lijantropique on May 28, 2014, 1:44 p.m.
Hello Bryukh, That was my point. The program runs without errors but nothing special happened (I was expecting some kind of print message). I found two websites talking about this feature (English/French): <a href="http://stackoverflow.com/questions/3038033/what-are-good-uses-for-python3s-function-annotations">http://stackoverflow.com/questions/3038033/what-are-good-uses-for-python3s-function-annotations</a> <a href="http://sametmax.com/les-annotations-en-python-3/">http://sametmax.com/les-annotations-en-python-3/</a> Regards, Lij

gyahun_dash on May 27, 2014, 3:39 p.m.
It is annotation introduced in py3. Let's try it.

veky on Feb. 2, 2015, 5:21 p.m.
They are annotations. However, they are used wrong. Yes, I know that there is no official semantics of annotations, but some things aren't subject to reinterpretation. First and most important, individual parameters have annotations, not a bunch of parameters together (PEP3107 speaks about nested parameters, but they are forbidden in Py3 anyway). So, "sides" is an annotation for the third parameter, "c". That's obviously not what you wanted. Second, the part after "->" should be an annotation of return value. Not of process used to calculate it. Implementation details like "using Heron's formula" belong in comments, or if you stretch definitions a bit, in the docstring. In no way they belong in annotation. The solution is fine otherwise, but the misuse of annotations really stands out. Even more because they're used in only one function.

aotus on Aug. 11, 2014, 7:47 p.m.
My solution was essentially the same, except that I defined my equivalent to areafunction globally. I think that your approach would redefine the areafunction dictionary each time that you call simple_areas(), am I right?

aotus on Aug. 12, 2014, 9:35 p.m.
Pardon the strange formatting in my message. It appears that the underscore character is interpreted as a flag for italics!

gyahun_dash on Aug. 13, 2014, 2:31 a.m.
When you use underscores in comments, you may insert \ in front of them.

gyahun_dash on Aug. 12, 2014, 6:37 p.m.
As you say, the dictionary is re-defined. If we need more speed, it should be defined globally like yours. Thank you.

ematorose on Sept. 27, 2014, 9:58 p.m.
I thought about doing it this way but opted for one def. I like this, it is so clear and nice.

gyahun_dash on Sept. 30, 2014, 3:04 p.m.
Thank you.

Mine

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