std::map<int, int> counts;

// load the values into the count-map

for (unsigned int i = 0; i < x.size(); ++i) {

++counts[x[i]];

}

// flatten the map to a vector

// contains the cluster names, i.e., "1 2 2", "2 2 2" etc

std::vector<int> cluster_names;

cluster_names.reserve(counts.size());

// contains the cluster counts

std::vector<int> cluster_counts;

cluster_counts.reserve(counts.size());

double total = 0;

for (auto it = counts.begin(); it != counts.end(); ++it) {

total += it->second;

cluster_names.push_back(it->first);

cluster_counts.push_back(it->second);

}

Rcpp::NumericVector vec(cluster_names.size());

for (unsigned int i = 0; i < cluster_names.size(); ++i) {

vec[i] = cluster_counts[i] / total;

}

vec.attr("names") = cluster_names;

return vec;