CODEWITHSUNDEEP
c++vector
Beatriz Gijón
Beatriz Gijón

Reputation: 45

Deleting repeated elements of a vector c++

So.. I have 2 vectors: xmax and ymax, which represent the x and y coordinates of a list of points. I want to delete the variables in which xmax[i]==xmax[i-1] and ymax[i]==ymax[i-1] (so... to sum up, I want to delete repeated points which have same coordinates). This is the code I am using:

std::vector<double> xx, yy;
        for (int i = 0; i < xmax.size(); i++) {
            if (i > 0 && xmax[i] == xmax[i - 1] && ymax[i]==ymax[i-1])
              continue;
            xx.push_back(xmax[i]);
            yy.push_back(ymax[i]);
        }

But I would like to know if there is a simple way of deleting the variables without creating a new vector for this.

Upvotes: 0

Views: 76

Answers (1)

scohe001
scohe001

Reputation: 15446

I'd advise switching to a single vector of pairs of ints (instead of two separate vectors):

std::vector<std::pair<int, int>> points = {{1, 1}, {5, 2}, {5, 2}, {7, 10}};

Then you can make use of std::unique().

If you define a comparator function:

bool point_compare(const std::pair<int, int> &p1, const std::pair<int, int> &p2) {
    return p1.first == p2.first && p1.second == p2.second;
}

Then you can use std::unique() like:

auto last = std::unique(points.begin(), points.end());
points.erase(last, points.end());

See it in action here: https://ideone.com/fZM9b2

Upvotes: 2

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