我怎样才能找到一个载体重复的元素 [英] how can I find repeated elements in a vector

问题描述

我有一个vector INT 其中可以包括最多4个元素和最小2，例如：

I have a vector of int which can include maximum 4 elements and minimum 2, for example :

std::vector<int> vectorDATA(X); // x means unknown here

我想要做的是消除重复例如，该元素：

What I want to do is to erase the elements that are repeated for example :

vectorDATA{1,2,2}     to vectorDATA{1,2}
vectorDATA{1,2,3}     to nothing changes
vectorDATA{2,2,2}     to vectorDATA{2}
vectorDATA{3,2,1,3}   to vectorDATA{3,2,1}
vectorDATA{1,2,1,2}   to vector{1,2} 

等

这里code简单：

cv::HoughLines(canny,lineQ,1,CV_PI/180,200);
        std::cout << " line Size "<<lineQ.size()<< std::endl;
        std::vector<int> linesData(lineQ.size());
        std::vector<int> ::iterator  it;
        if(lineQ.size() <=4 && lineQ.size() !=0 ){
            if(lineQ.size()==1){
                break;
            }else {
            for ( int i = 0; i<lineQ.size();i++){
                linesData[i] = lineQ[i][1]; // my comparison parameter is the lineQ[i][1]
            }

//根据我得到的答案我想这一点，但我真的不如何继续？

// based on the answer I got I'm trying this but I really don't how to continue ?

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

我试图用并做的，而循环，但我没有得到它，而功能的std :: adjacent_find 这有一个条件，即该元素应该是连续的。照片 也许是容易的，但我就是不明白这一点！ 感谢您的帮助！

I tried use a for and do while loop, but I didn't get it, and the function std::adjacent_find this has a condition that the elements should be consecutive.
Maybe it's easy but I just don't get it ! thanks for any help !

推荐答案

最简单的办法是有点那么独特的擦除，但是这改变秩序。

The easy way is sort then unique-erase, but this changes order.

C ++的11阶preserving的方法是创建一个 unordered_set＆LT; INT＆GT; S; 做：

The c++11 order preserving way is to create an unordered_set<int> s; and do:

unordered_set<int> s;
vec.erase(
  std::remove_if( vec.begin(),vec.end(), // remove from vector
    [&](int x)->bool{
      return !std::get<1>(s.insert(x)); // true iff the item was already in the set
    }
  ),
  vec.end() // erase from the end of kept elements to the end of the `vec`
);

这是使用remove擦除成语 unordered_set 来检测是否有重复。

which is the remove-erase idiom using the unordered_set to detect duplicates.

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