CODEWITHSUNDEEP
c++vector
Ugur Sahin
Ugur Sahin

Reputation: 47

How to compare two vectors of a same object and get other elements

I want to compare two object vector element and get the other vector elements of the same object accordingly. For example object has a vector; foo1.a=[4 2 1 3] foo2.a=[2 1 4] I want to find same elements and then get the other vectors containment correspondingly such as foo1.b=[8 8 2 10] and foo2.b=[8 2 8] according to findings I get from foo.a. I tried to compare two vectors in the loops and then get the same, but I failed.

Upvotes: 2

Views: 2843

Answers (1)

congusbongus
congusbongus

Reputation: 14622

Given two vectors:

std::vector<int> v1; // {4, 2, 1, 3};
std::vector<int> v2; // {2, 1, 4};

First, sort the two vectors so that it's easy to find common elements:

std::sort(v1); // {1, 2, 3, 4}
std::sort(v2); // {1, 2, 4}

Use set_intersection to find common elements:

std::vector<int> vi;
std::set_intersection(v1.begin(), v1.end(), v2.begin(), v2.end(), vi.begin()); // {1, 2, 4}

Use set_difference to find unique elements:

std::vector<int> vd;
std::set_difference(v1.begin(), v1.end(), v2.begin(), v2.end(), vd.begin()); // {3}

Upvotes: 4

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