不知道这是什么“直方图代码”在做MATLAB [英] Not sure what this 'histogram code' is doing in MATLAB

问题描述

我有以下代码给我，但我不知道这里的逻辑是什么。这个想法，我相信，这将直方图/量化我的数据。这是代码：

输入：

  x = 180 * rand（1,1000）; ％1000点从0到180度。 
 binWidth = 20; ％我想binWidth是20度。 
  

主要功能：

 ％------------------------------------------ ------------------------------- 
％计算最小的仓中心x1小于或等于x 
％--------------------------------------------- ---------------------------- 
 
 function [x1，b1] = computeLowerHistBin（x，binWidth）
 
％Bin index 
 bin = floor（x./binWidth  -  0.5）; 
 
％bin center x1 
 x1 = binWidth *（bin + 0.5）; 
 
％添加2到基于1的索引
 b1 = bin + 2; 
 end 
  

最后，最终的量化数据：

  w = 1  - （x  -  x1）./ binWidth 
  

这里是我没有得到：我不明白 - 在所有 - 只是为什么 x1 是计算的方式，而且为什么/如何 w 是按照它的方式计算的。事实上，在所有的事情， w 困惑我最。我真的不明白这里的逻辑，或什么是真正的意图。将欣赏这个逻辑的详细阐释。

解决方案

他正在使用 lb< = x&并分割 [ - 10,10]，[10,30]，[3080]中的 [0,180] ，40）...，[150,170]，[170,190] 。

假设 x = 180 ，则：

  bin = floor（180 / 20-0.5）= floor（9-0.5）= floor （8.5）= 8; 
  

而如果 x = 0 ：

  bin = floor（`0 / 20-0.5）= floor（-0.5） 
  

分别转换为 x1 = 20 *（8 + 0.5）= 170 和 x1 = -10 ，这看起来像函数建议 lowerHistBin（） / p>



最后， w 只是测量 x 来自相应的下部bin x1 。注意 w 在（0,1]中， w 因此，如果x表示接近170，则 w ，并且当 x-> x1 + binWidth / code>将接近 1 - （170-150）/ 20 = 0 。

I have following code that was given to me, but I am not sure at all as to what the logic here is. The idea, I believe, is that this will histogram/quantize my data. Here is the code:

The input:

x = 180.*rand(1,1000); %1000 points from 0 to 180 degrees.
binWidth = 20;         %I want the binWidth to be 20 degrees.

The main function:

% -------------------------------------------------------------------------
% Compute the closest bin center x1 that is less than or equal to x
% -------------------------------------------------------------------------

function [x1, b1] = computeLowerHistBin(x, binWidth)

% Bin index
bin = floor(x./binWidth - 0.5);

% Bin center x1
x1 = binWidth * (bin + 0.5);

% add 2 to get to 1-based indexing
b1 = bin + 2;
end

Finally, the final 'quantized' data:

w = 1 - (x - x1)./binWidth

Here is what I do not get: I do not understand - at all - just why exactly x1 is computed the way it is, and also why/how w is computed the way it is. In fact, of all the things, w confuses me the most. I literally cannot understand the logic here, or what is really intended. Would appreciate a detailed elucidation of this logic. Thanks.

解决方案

He is binning with lb <= x < up and splitting the interval [0,180] in [-10,10), [10, 30), [30,40) ..., [150,170), [170,190).

Suppose x = 180, then:

bin = floor(180/20-0.5) = floor(9-0.5) = floor(8.5) = 8; 

while if x = 0:

bin = floor(`0/20-0.5) = floor(-0.5) = floor(-1) = -1; 

which respectively translate into x1 = 20 * (8+0.5) = 170 and x1 = -10 which seems like what the function suggests lowerHistBin().

In the end, w simply measures how far the point x is from the corresponding lower bin x1. Notice that w is in (0,1], with w being 1 when x = x1 and approaching 0 when x -> x1+binWidth. So, if x say approaches 170, then w will approach 1 - (170-150)/20 = 0.

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