如何elminate的＆QUOT;增加了一倍＆QUOT;在C向量元素+ [英] how to elminate the "doubled" elements of a vector in c++

问题描述

我使用了 HoughLines 来检测线路在一个框架，将保存在 CV ::矢量＆lt线路信息;简历:: Vec2f＆GT; 这是我处理的二维数组，我感兴趣的是第二个，它的线的角度，我想只保留有一个角度差大于<$ C线$ C> 1.5弧度为这里我我所做的：

I'm using the HoughLinesto detect line in a frame, the lines information are saved in a cv::vector<cv::Vec2f> which I handle as two dimensional array, I'm interested in the second one , it the angle of the line, I want to keep only the lines that have a angle difference greater than 1.5 rad for that here I what I did :

.............................
cv::vector<cv::Vec2f> lineQ;
..............................

  // ordring the vector based on the angle value in rad 
for ( int i = 0 ; i< lineQ.size()-1; i++){
                for(int j= i+1;j<lineQ.size();j++){
                        if(lineQ[i][1] > lineQ[j][1]){
                            tmp = lineQ[i];
                            lineQ[i] = lineQ[j];
                            lineQ[j] = tmp;
                        }           
                }
            }

现在我想基于角度彼此之间的矢量元素比较

now I want to compare the vector elements between each other based on the angle

cv::vector<cv::Vec2f> line;
for ( int i = 0 ; i< lineQ.size()-1; i++){
                for ( int j= i+1; j<lineQ.size(); j++){
            if(fabs(lineQ[i][1] - lineQ[j][1])>1.5){
                        line.push_back(lineQ[i]);

                        }
                }
            }

这适用于2线，但是当我到了3白衣假设1.3rad作为一个角的大小行  比2，我虽然用删除但是这个改变我向量的大小！

this works for 2 lines but when I got 3 whit let's say 1.3rad as an angle the size of line is than 2. I though to use erase but this change the size of my vector !

推荐答案

一种选择是提供一个软等于，以的std :: unique_copy ：

One option is to supply a soft "equals" to std::unique_copy:

std::unique_copy(lineQ.begin(), lineQ.end(), std::back_inserter(line),
                 [](const cv::Vec2f & a, const cv::Vec2f & b) {
                     return b[1] - a[1] <= 1.5;
                 });

旁注：你也可以避免写自己的排序的努力（冒泡排序仅仅是最糟糕的选择。），并使用标准库。像这样的东西应该工作：

Sidenote: You can also avoid the effort of writing your own sort (Bubble sort is just about the worst choice.) and use the standard library. Something like this ought to work:

std::sort(lineQ.begin(), lineQ.end(),
          [](const cv::Vec2f & a, const cv::Vec2f & b) {
              return a[1] < b[1];
          })).

（以上code假设C ++ 11，我们大多数人都通过了。如果你被困在一个早期版本，你可以写几个函数子类来代替。）

(The above code assumes C++11, which most of us have by now. If you're stuck on an earlier version, you can write a couple of functor classes instead.)

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