C ++帮助查找地图中的最大值 [英] C++ Help finding the max value in a map

问题描述

所以我一直在寻找，尝试了许多不同的东西，在这一点上，我的头脑已经几乎融化，我不能直视。我一直在做一个基本的程序，以找到一个向量的最大值，最小值，中值，方差，模式等。一切都进行得很顺利，直到我进入模式。我甚至不能开始我想要的方式。

So I've been searching around and have tried many different things and at this point my mind has pretty much melted and I can't think straight. I've been doing a basic program to find the max, min, median, variance, mode etc. of a vector. Everything went fine until I got to the mode. I can't even get started the way I want to.

我看到它的方式，我应该能够循环通过向量，并为每个发生的数字我在地图上增加一个键。找到具有最高价值的密钥将是发生最多的密钥。与其他键比较会告诉我，如果它是一个单倍或没有模式答案。

The way I see it, I should be able to loop through the vector, and for each number that occurs I increment a key on the map. Finding the key with the highest value would then be the one that occured the most. Comparing to other keys would tell me if it's a single multiple or no mode answer.

Unfortuneatley我遇到麻烦了，因为我没有经验的地图，并已经运行各种兼容性和语法错误。我知道我现在没有什么意义，但它在哪里我碰撞了。这里的代码块已经导致我这么多的麻烦。

Unfortuneatley I've run into trouble right off the bat with this as I have no experince with maps and have been running into all kinds of compatibility and syntax errors. I know what I have now doesn't make sense but it sort of where I've crashed into. Here's the chunk of code that's been causing me so much trouble.

map<int,unsigned> frequencyCount;
// This is my attempt to increment the values
// of the map everytime one of the same numebers 
for(size_t i = 0; i < v.size(); ++i)
    frequencyCount[v[i]]++;

unsigned currentMax = 0;
unsigned checked = 0;
unsigned maax = 0;
for(auto it = frequencyCount.cbegin(); it != frequencyCount.cend(); ++it )
    //checked = it->second;
    if (it ->second > currentMax)
    {
        maax = it->first;
    }
    //if(it ->second > currentMax){
    //v = it->first

cout << " The highest value within the map is: " << maax << endl;

这里可以看到整个程序。 http://pastebin.com/MzPENmHp

The entire program can be seen here. http://pastebin.com/MzPENmHp

您可以提供任何帮助将是巨大的赞赏。先谢谢你。

Any help you guys can offer would be GREATLY appreicated. Thank you in advance.

推荐答案

您从未在代码中更改 currentMax

You never changed currentMax in your code.

map<int,unsigned> frequencyCount;
for(size_t i = 0; i < v.size(); ++i)
    frequencyCount[v[i]]++;

unsigned currentMax = 0;
unsigned arg_max = 0;
for(auto it = frequencyCount.cbegin(); it != frequencyCount.cend(); ++it ) }
    if (it ->second > currentMax) {
        arg_max = it->first;
        currentMax = it->second;
    }
}
cout << "Value " << arg_max << " occurs " << currentMax << " times " << endl;

另一种找到模式的方法是对向量​​进行排序并循环遍历它一次，其中值发生变化的指数。

Another way to find the mode is to sort the vector and loop through it once, keeping track of the indices where the values change.

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