Reading proper decimal values on lower numbers?



  • Hi,

    I'm writing a script that exports the position of an object. In the process, I'm truncating them to only four decimals.
    Wrote the a truncate function. It works but not on low numbers.

    For example,

    Actual Position: Vector(0, 139.213, 93.26)
    X-Position: 2.42398958609e-05
    Resulting truncation: 2.4239
    

    It turns out the script reads the pseudo decimal to an actual decimal. Is there a way to read the numbers as this 0.0000242398958609 so the function works as expected or should I revise the function?

    Here is the current code:

    def truncate(num):
        num_str = str(num)
        num = num_str.split(".")
        num_real = num[0]
        num_dec  = num[1][:4]
        
        new_num_str = "{}.{}".format(num_real, num_dec)
        new_num = float(new_num_str)
    
        return new_num
    


  • Hi,

    that your script is not working has not anything to do with pseudo decimals, but the fact that you are treating numbers as strings (which is generally a bad idea) in a not very careful manner. When you truncate the string representation of a number which is represented in scientific notation (with an exponent), then you also truncate that exponent and therefor change the value of the number.

    To truncate a float you can either take the floor of my_float * 10 ** digits and then divide by 10 ** digits again or use the keyword round.

    data = [0.03659665587738824,
            0.00018878623163019122,
            1.1076812650509394e-03,
            1.3882258325566638e-06]
    
    for n in data:
        rounded = round(n, 4)
        floored = int(n * 10000) / 10000
        print(n, rounded, floored)
    
    0.03659665587738824 0.0366 0.0365
    0.00018878623163019122 0.0002 0.0001
    0.0011076812650509394 0.0011 0.0011
    1.3882258325566637e-06 0.0 0.0
    [Finished in 0.1s]
    

    Cheers
    zipit



  • RE: treating numbers as strings (which is generally a bad idea) in a not very careful manner.
    THanks for the reminder. I initially thought I could get away with such a rudimetary approach

    RE: code
    Interesting. Your algorithm is way more useful. Thanks for sharing.



  • Hello,

    Thanks again @zipit for the fast and nice reply 👍

    I also move this thread to general programming as it's not related to Cinema 4D :)

    Cheers,
    Manuel


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