我正在为我的妻子编写一个程序，以帮助我们尝试决定她应该申请哪些医学院。但是，我遇到了一个问题，我试图提取在 4 种不同情况下出现在前 20 名结果中的学校。
例如，在其中一个案例中，我将城市的收入中位数除以城市的平均房价。这会返回一个 double ，然后我创建一个新 vector ，然后根据该数字从最高到最低对该 vector 进行排序。我对池中的其他 3 个 vector 执行类似的操作，并应用不同的案例。
我知道我可以强制执行此操作并使用嵌套的 for 循环提取名称，但我很想知道是否有一种方法可以快速有效地完成此操作。到目前为止，这是我的尝试。 (注意，这只是一个例子，我的实际代码里面有30所学校)。
#include <algorithm>
#include <iterator>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
struct Schools
{
Schools(std::string n = "", double h = 0.0, double t = 0.0, int r = 0, int w = 0) : name(n), housing(h), tuition(t), rank(r), weight(w){};
std::string name;
double housing;
double tuition;
int rank;
int weight;
};
void load(std::vector<std::shared_ptr<Schools>> &v, std::string n, double h, double t, int r, int w)
{
auto newSchool = std::make_shared<Schools>(n,h,t,r,w);
v.emplace_back(newSchool);
}
void init(std::vector<std::shared_ptr<Schools>> &schools)
{
load(schools,"School1",40.3,20.0,3,6);
load(schools,"School2",10.3,10.4,5,1);
load(schools,"School3",33.3,23.5,1,2);
load(schools,"School4",8.5,15.5,4,8);
}
auto findIntersection(auto &a, auto &b)
{
std::vector<std::shared_ptr<Schools>> in;
std::set_intersection(begin(a),end(a),begin(b),end(b),std::back_inserter(in));
return in;
}
auto findCommon(auto &housing, auto &tuition, auto &rank, auto &weight)
{
std::vector<std::shared_ptr<Schools>> inCommon;
inCommon = findIntersection(housing,tuition);
inCommon = findIntersection(inCommon,rank);
inCommon = findIntersection(inCommon,weight);
return inCommon;
}
bool compareHM(const std::shared_ptr<Schools> &a, const std::shared_ptr<Schools> &b)
{
return a->housing < b->housing;
}
bool compareT(const std::shared_ptr<Schools> &a, const std::shared_ptr<Schools> &b)
{
return a->tuition < b->tuition;
}
bool compareRank(const std::shared_ptr<Schools> &a, const std::shared_ptr<Schools> &b)
{
return a->rank > b->rank;
}
bool compareWeight(const std::shared_ptr<Schools> &a, const std::shared_ptr<Schools> &b)
{
return a->weight > b->weight;
}
int main()
{
std::vector<std::shared_ptr<Schools>> schools;
init(schools);
std::vector<std::shared_ptr<Schools>> sortByHousing = schools;
std::vector<std::shared_ptr<Schools>> sortByTuition = schools;
std::vector<std::shared_ptr<Schools>> sortByRank = schools;
std::vector<std::shared_ptr<Schools>> sortByWeight = schools;
std::sort(begin(sortByHousing),end(sortByHousing), compareHM);
std::sort(begin(sortByTuition),end(sortByTuition), compareT);
std::sort(begin(sortByRank),end(sortByRank), compareRank);
std::sort(begin(sortByWeight),end(sortByWeight), compareWeight);
std::vector<std::shared_ptr<Schools>> commonSchools = findCommon(sortByHousing,sortByTuition,sortByRank,sortByWeight);
for (auto && e: commonSchools)
{
std::cout << e->name << std::endl;
}
}
当我尝试使用 std::set_intersection 时遇到问题，然后我很快意识到我不能做类似 begin(a)->name 的事情.同样，我试图提取出现在我所拥有的 4 个案例中的常见名称。我该如何着手实现呢？我对 std::set_intersection 的想法离得不远吗？
谢谢!
编辑:
这是我的 functionThatCompares
bool compareTuition(const std::shared_ptr<Schools> &a, const std::shared_ptr<Schools> &b)
{
return a->tuition < b->tuition;
}
编辑 2:示例输出
The top 20 sorted by Median/House are:
Name of Institution Median/House Price Tuition Over 8 Years Has Space Industry? Score
University of Alabama 0.463577 0.722279 1 0.641825
University of Maryland 0.38124 0.722617 1 0.527583
Johns Hopkins Univerty School of Medicine 0.38124 0.606103 1 0.629002
Indiana University 0.335939 0.501944 0 0.669276
Ohio State University 0.32499 0.610704 1 0.532156
Perelman School of Medicine 0.26908 0.653143 1 0.411977
Duke University School of Medicine 0.246991 0.66683 1 0.370395
University of Wisconsin 0.226581 0.64686 0 0.350278
Chicago Medical School 0.221883 0.648157 0 0.342329
Northwestern University 0.221883 0.677341 0 0.32758
Case Western Reserve 0.211817 0.536384 1 0.394898
Emory University 0.206169 0.576814 1 0.357427
Geisel School of Medicine 0.205529 0.71526 0 0.287349
University of Massachusetts 0.19562 0.64686 1 0.302414
Medical University of SC 0.185816 0.354728 0 0.523827
University of North Carolina 0.176684 0.6637 0 0.26621
University of Michigan Medical School 0.158465 0.637237 1 0.248675
Rutgers New Jersey Medical School 0.140412 0.722115 0 0.194446
University of Utah 0.140142 0.311285 0 0.450205
Georgetown University 0.128883 0.604001 1 0.213382
The top 20 sorted by Tuition are:
Name of Institution Median/House Price Tuition Over 8 Years Has Space Industry? Score
University of Utah 0.140142 0.311285 0 0.450205
Medical University of SC 0.185816 0.354728 0 0.523827
University of California, LA 0.07633 0.47547 1 0.160536
Indiana University 0.335939 0.501944 0 0.669276
University of California, SD 0.109214 0.531397 1 0.205523
Case Western Reserve 0.211817 0.536384 1 0.394898
Emory University 0.206169 0.576814 1 0.357427
Icahn School of Medicine 0.0822029 0.585946 1 0.140291
Georgetown University 0.128883 0.604001 1 0.213382
Johns Hopkins Univerty School of Medicine 0.38124 0.606103 1 0.629002
Ohio State University 0.32499 0.610704 1 0.532156
University of Virgina School of Medicine 0.123755 0.630067 1 0.196415
University of Michigan Medical School 0.158465 0.637237 1 0.248675
NY University School of Medicine 0.0822029 0.642516 1 0.127939
Tufts University School of Medicine 0.100302 0.644314 1 0.155672
University of Massachusetts 0.19562 0.64686 1 0.302414
University of Wisconsin 0.226581 0.64686 0 0.350278
Chicago Medical School 0.221883 0.648157 0 0.342329
Perelman School of Medicine 0.26908 0.653143 1 0.411977
Standford University School of Medicine 0.0780054 0.656658 1 0.118791
The top 20 sorted by Median/House and Loweset Tution are:
Name of Institution Median/House Price Tuition Over 8 Years Has Space Industry? Score
University of Maryland 0.38124 0.722617 1 0.527583
Chicago Medical School 0.221883 0.648157 0 0.342329
University Of Washington 0.0973689 0.761413 1 0.127879
University of Alabama 0.463577 0.722279 1 0.641825
Rutgers New Jersey Medical School 0.140412 0.722115 0 0.194446
Geisel School of Medicine 0.205529 0.71526 0 0.287349
Ohio State University 0.32499 0.610704 1 0.532156
Harvard Medical School 0.100302 0.710787 1 0.141114
Duke University School of Medicine 0.246991 0.66683 1 0.370395
Boston University School of Medicine 0.100302 0.710787 1 0.141114
Perelman School of Medicine 0.26908 0.653143 1 0.411977
University of Wisconsin 0.226581 0.64686 0 0.350278
University of North Carolina 0.176684 0.6637 0 0.26621
Standford University School of Medicine 0.0780054 0.656658 1 0.118791
Johns Hopkins Univerty School of Medicine 0.38124 0.606103 1 0.629002
Northwestern University 0.221883 0.677341 0 0.32758
Indiana University 0.335939 0.501944 0 0.669276
Case Western Reserve 0.211817 0.536384 1 0.394898
Emory University 0.206169 0.576814 1 0.357427
University of Massachusetts 0.19562 0.64686 1 0.302414
The top 20 sorted by Score (Median/House * Tuition/Salary) are:
Name of Institution Median/House Price Tuition Over 8 Years Has Space Industry? Score
Indiana University 0.335939 0.501944 0 0.669276
University of Alabama 0.463577 0.722279 1 0.641825
Johns Hopkins Univerty School of Medicine 0.38124 0.606103 1 0.629002
Ohio State University 0.32499 0.610704 1 0.532156
University of Maryland 0.38124 0.722617 1 0.527583
Medical University of SC 0.185816 0.354728 0 0.523827
University of Utah 0.140142 0.311285 0 0.450205
Perelman School of Medicine 0.26908 0.653143 1 0.411977
Case Western Reserve 0.211817 0.536384 1 0.394898
Duke University School of Medicine 0.246991 0.66683 1 0.370395
Emory University 0.206169 0.576814 1 0.357427
University of Wisconsin 0.226581 0.64686 0 0.350278
Chicago Medical School 0.221883 0.648157 0 0.342329
Northwestern University 0.221883 0.677341 0 0.32758
University of Massachusetts 0.19562 0.64686 1 0.302414
Geisel School of Medicine 0.205529 0.71526 0 0.287349
University of North Carolina 0.176684 0.6637 0 0.26621
University of Michigan Medical School 0.158465 0.637237 1 0.248675
Georgetown University 0.128883 0.604001 1 0.213382
University of California, SD 0.109214 0.531397 1 0.205523
编辑 3:
对于那些试图编译这个程序的人，我深表歉意。它现在可以编译并运行。
最佳答案
当您执行诸如排序或 set_intersection 之类的操作时，您可以指定应该如何进行比较。如果您不指定任何内容，operator<将使用该类型(如果已定义)。
在这种情况下，您可能想使用 partial_sort_copy 而不是 sort .这将使您获得(例如)每次排序的前 10 所学校。
然后您必须按名称重新排序以执行 set_intersection。
然后您将执行 set_intersection 以获取这些集合之间共有的学校。
下面是一些演示代码:
#include <iostream>
#include <algorithm>
#include <vector>
#include <memory>
struct School
{
std::string name;
double housing;
double tuition;
int rank;
int weight;
// default comparison to use if nothing else is specified:
bool operator<(School const &other) const { return name < other.name; }
};
int main()
{
std::vector<School> schools{
{"School1", 40.3, 20.0, 3, 6},
{"School2", 10.3, 10.4, 5, 1},
{"School3", 33.3, 23.5, 1, 2},
{"School4", 8.5, 15.5, 4, 8}
};
// We specify the size of each of these as 3, so when we do the
// partial_sort_copy, it'll fill in the top 3 for that category.
std::vector<School> byHousing(3);
std::vector<School> byRank(3);
std::vector<School> byWeight(3);
std::partial_sort_copy(schools.begin(), schools.end(), byHousing.begin(), byHousing.end(),
[](School const &a, School const &b) { return a.housing < b.housing; });
std::partial_sort_copy(schools.begin(), schools.end(), byRank.begin(), byRank.end(),
[](School const &a, School const &b) { return a.rank < b.rank; });
std::partial_sort_copy(schools.begin(), schools.end(), byWeight.begin(), byWeight.end(),
[](School const &a, School const &b) { return a.weight < b.weight; });
std::sort(byHousing.begin(), byHousing.end());
std::sort(byRank.begin(), byRank.end());
std::sort(byWeight.begin(), byWeight.end());
std::vector<School> temp, commonSchools;
std::set_intersection(byHousing.begin(), byHousing.end(), byRank.begin(), byRank.end(),
std::back_inserter(temp));
std::set_intersection(temp.begin(), temp.end(), byWeight.begin(), byWeight.end(),
std::back_inserter(commonSchools));
std::cout << "Common Schools\n";
for (auto const & e: commonSchools)
{
std::cout << e.name << "\n";
}
}
结果:
Common Schools
School3
顺便说一句，在我看来它就像使用 shared_ptr 编写代码一样打算添加一些额外的工作(并且可能没有足够的关注)所以我没有打扰。我还省略了按学费筛选/分类——两者几乎相同。
关于c++ - 如何有效地比较相似名称的多个结构 vector ？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51429298/
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