在地图中寻找最大值 [英] Finding the max value in a map

问题描述

我一直在做一个基本的程序来查找向量的最大值、最小值、中值、方差、众数等.一切顺利，直到我进入模式.

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.

在我看来，我应该能够遍历向量，并且对于出现的每个数字，我都会在地图上增加一个键.找到具有最高值的键将是出现次数最多的键.与其他键相比，我会知道它是单多还是无模式应答.

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 occurred the most. Comparing to other keys would tell me if it's a single multiple or no mode answer.

这是给我带来很多麻烦的代码块.

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;

可以在这里看到整个程序.http://pastebin.com/MzPENmHp

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

推荐答案

您从未更改代码中的 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一次，跟踪值发生变化的索引.

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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