我该如何以更加惯用和有效的方式重新编写此MATLAB代码? [英] How can I re-write this MATLAB code in a more idiomatic and efficient way?

问题描述

这里是要求:输入是一个数字，它将一个图像分成几个相等的部分.例如，如果输入为4，它将返回3个部分:值分别为imgSize/4 imgSize/4 * 2和imgSize/4 * 3.

Here is the requirement: the input is a number which will divide an image into several equal part. For example, if the input is 4, it will return 3 parts: the values are the imgSize/4 imgSize/4 * 2 and imgSize/4 * 3.

如果输入为n，则它将返回n - 1元素，如以下实现所示:

If the input is n, then it will return n - 1 elements, as in the following implementation:

if (colorLevel == 8)
    divide_thres = [ round(imgSize/8) round(imgSize/8)*2 round(imgSize/8)*3 round(imgSize/8)*4 
        round(imgSize/8)*5 round(imgSize/8)*6 round(imgSize/8)*7 ];
elseif (colorLevel == 4)
    divide_thres = [ round(imgSize/4) round(imgSize/4)*2 round(imgSize/4)*3 ];
elseif (colorLevel == 3)
    divide_thres = [ round(imgSize/3) round(imgSize/3)*2 ];
end

我想允许用户输入2到255之间的值，然后自动生成与该输入相对应的divide_thres.如何重新编写此代码以提高效率?

I want to allow the user to input a value between 2 and 255, and then automatically generate the divide_thres corresponding to that input. How can I re-write this code to be more efficient?

推荐答案

您的代码有几个问题:

• 在每种情况下，您都不必要多次将imgSize除以相同的因子(而不是一劳永逸).
• 您执行了许多手动"标量乘法，但是您可以将标量值乘以由范围1 : colorLevel - 1生成的向量.

• 由于可以很容易地从colorLevel的值计算出生成的divide_thres向量的长度，因此无需在if语句中分别处理每种情况.

• In each case, you unnecessarily divide imgSize by the same factor multiple times (instead of just once and for all).
• You perform many "manual" scalar multiplications, but you could simply multiply the scalar value by a vector generated by the range 1 : colorLevel - 1.

• Because the length of the resulting divide_thres vector can be easily computed from the value of colorLevel, there is no need to treat each case separately in an if statement.

此外，即使在imgSize = 3，4和8情况下，即使必须以不同的方式计算长度，您也最好使用switch语句代替if语句，因为前者可以为您节省每次编写imgSize == ...的麻烦，因为它容易出错，并且会产生某种形式的代码重复.

Moreover, even if you had to compute the length in a different manner for the cases imgSize = 3, 4, and 8, you would be better off using a switch statement instead of an if statement, because the former would save you the trouble of writing imgSize == ... each time, which is prone to errors and a form of code duplication.

这是一种非常简化的方法:

Here's a much simplified approach:

if 2 <= colorLevel && colorLevel <= 255
    divide_thres = round(imgSize / colorLevel) * (1 : colorLevel - 1);
else
    error('invalid colorLevel value') % (or some other informative message)
end

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