How to Sort Multiple Vectors Simultaneously Based on a Reference Vector?

Sorting Vectors Based on an External Reference Vector

In situations where multiple vectors of equal length are present, sorting one vector requires a solution that simultaneously transforms all other vectors accordingly.

Consider the following scenario:

std::vector<int> Index = { 3, 1, 2 };
std::vector<std::string> Values = { "Third", "First", "Second" };

Transformation: Index is sorted.

Expected Outcome: Values should be sorted as well.

One approach involves creating a vector containing both the original index and the elements from the sorting-dictating vector:

typedef vector<int>::const_iterator myiter;

vector<pair<size_t, myiter>> order(Index.size());

size_t n = 0;
for (myiter it = Index.begin(); it != Index.end(); ++it, ++n)
    order[n] = make_pair(n, it);

Next, this vector is sorted:

struct ordering {
    bool operator ()(pair<size_t, myiter> const&amp; a, pair<size_t, myiter> const&amp; b) {
        return *(a.second) < *(b.second);
    }
};

sort(order.begin(), order.end(), ordering());

The sorted order allows for the rearrangement of other vectors:

template <typename T>
vector<T> sort_from_ref(
    vector<T> const& in,
    vector<pair<size_t, myiter>> const& reference
) {
    vector<T> ret(in.size());

    size_t const size = in.size();
    for (size_t i = 0; i < size; ++i)
        ret[i] = in[reference[i].first];

    return ret;
}

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