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intorduce minPoints option
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@zmiao
zmiao committed Jun 4, 2020
1 parent 03c026c commit 7ee4e4e
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Showing 2 changed files with 109 additions and 31 deletions.
73 changes: 48 additions & 25 deletions include/supercluster.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,7 @@ struct Options {
std::uint8_t maxZoom = 16; // max zoom level to cluster the points on
std::uint16_t radius = 40; // cluster radius in pixels
std::uint16_t extent = 512; // tile extent (radius is calculated relative to it)
std::size_t minPoints = 2; // minimum points to form a cluster

std::function<property_map(const property_map &)> map =
[](const property_map &p) -> property_map { return p; };
Expand Down Expand Up @@ -286,41 +287,63 @@ class Supercluster {

p.visited = true;

auto num_points = p.num_points;
point<double> weight = p.pos * double(num_points);
const auto num_points_origin = p.num_points;
auto num_points = num_points_origin;

auto clusterProperties = p.properties ? *p.properties : property_map{};
std::uint32_t id = static_cast<std::uint32_t>((i << 5) + (zoom + 1));

// find all nearby points
// count the number of points in a potential cluster
previous.tree.within(p.pos.x, p.pos.y, r, [&](const auto &neighbor_id) {
assert(neighbor_id < previous.clusters.size());
auto &b = previous.clusters[neighbor_id];

const auto &b = previous.clusters[neighbor_id];
// filter out neighbors that are already processed
if (b.visited) {
return;
}

b.visited = true;
b.parent_id = id;

// accumulate coordinates for calculating weighted center
weight += b.pos * double(b.num_points);
num_points += b.num_points;

if (options_.reduce && b.properties) {
// apply reduce function to update clusterProperites
options_.reduce(clusterProperties, *b.properties);
if (!b.visited) {
num_points += b.num_points;
}
});

if (num_points == 1) {
clusters.emplace_back(weight, 1, p.id, clusterProperties);
} else {
auto clusterProperties = p.properties ? *p.properties : property_map{};
if (num_points >= options_.minPoints) { // enough points to form a cluster
point<double> weight = p.pos * double(num_points_origin);
const std::uint32_t id = static_cast<std::uint32_t>((i << 5) + (zoom + 1));

// find all nearby points
previous.tree.within(p.pos.x, p.pos.y, r, [&](const auto &neighbor_id) {
assert(neighbor_id < previous.clusters.size());
auto &b = previous.clusters[neighbor_id];

// filter out neighbors that are already processed
if (b.visited) {
return;
}

b.visited = true;
b.parent_id = id;

// accumulate coordinates for calculating weighted center
weight += b.pos * double(b.num_points);

if (options_.reduce && b.properties) {
// apply reduce function to update clusterProperites
options_.reduce(clusterProperties, *b.properties);
}
});
p.parent_id = id;
clusters.emplace_back(weight / double(num_points), num_points, id,
clusterProperties);
} else {
clusters.emplace_back(p.pos, 1, p.id, clusterProperties);
if (num_points > 1) {
previous.tree.within(p.pos.x, p.pos.y, r, [&](const auto &neighbor_id) {
assert(neighbor_id < previous.clusters.size());
auto &b = previous.clusters[neighbor_id];
// filter out neighbors that are already processed
if (b.visited) {
return;
}
b.visited = true;
clusters.emplace_back(b.pos, 1, b.id,
b.properties ? *b.properties : property_map{});
});
}
}
}

Expand Down
67 changes: 61 additions & 6 deletions test/test.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,16 +9,17 @@
#include <iostream>
#include <vector>

int main() {
std::FILE *fp = std::fopen("test/fixtures/places.json", "r");
mapbox::feature::feature_collection<double> parseFeatures(const char *filename) {
std::FILE *fp = std::fopen(filename, "r");
char buffer[65536];
rapidjson::FileReadStream is(fp, buffer, sizeof(buffer));

rapidjson::Document d;
d.ParseStream(is);

std::fclose(fp);
const auto &json_features = d["features"];

assert(json_features.IsArray());
mapbox::feature::feature_collection<double> features;
features.reserve(json_features.Size());

Expand All @@ -27,13 +28,41 @@ int main() {
const auto lng = json_coords[0].GetDouble();
const auto lat = json_coords[1].GetDouble();
mapbox::geometry::point<double> point(lng, lat);

mapbox::feature::feature<double> feature{ point };
feature.properties["name"] = std::string((*itr)["properties"]["name"].GetString());
feature.properties["scalerank"] =
std::uint64_t((*itr)["properties"]["scalerank"].GetUint64());
const auto &properties = (*itr)["properties"];
const auto readProperty = [&feature, &properties](const char *key) {
if (properties.HasMember(key)) {
const auto &value = properties[key];
if (value.IsNull())
feature.properties[key] = std::string("null");
if (value.IsString())
feature.properties[key] = std::string(value.GetString());
if (value.IsUint64())
feature.properties[key] = std::uint64_t(value.GetUint64());
if (value.IsDouble())
feature.properties[key] = value.GetDouble();
}
};
readProperty("name");
readProperty("scalerank");
readProperty("lat_y");
readProperty("long_x");
readProperty("region");
readProperty("featureclass");
readProperty("comment");
readProperty("name_alt");
readProperty("subregion");
features.push_back(feature);
}

return features;
}

int main() {
const auto features = parseFeatures("test/fixtures/places.json");

// ----------------------- test 1 ------------------------------------
mapbox::supercluster::Options options;
mapbox::supercluster::Supercluster index(features, options);

Expand Down Expand Up @@ -80,6 +109,7 @@ int main() {
assert(leaves[8].properties["name"].get<std::string>() == "Miquelon");
assert(leaves[9].properties["name"].get<std::string>() == "Cape Bauld");

// ----------------------- test 2 ------------------------------------
mapbox::supercluster::Options options2;
options2.radius = 60;
options2.extent = 256;
Expand All @@ -105,6 +135,8 @@ int main() {
iter2->second.get<std::uint64_t>());
}
};

// ----------------------- test 3 ------------------------------------
mapbox::supercluster::Options options3;
options3.map = map;
options3.reduce = reduce;
Expand All @@ -116,6 +148,7 @@ int main() {
assert(tile3[0].properties.count("sum") != 0);
assert(tile3[0].properties["sum"].get<std::uint64_t>() == 69);

// ----------------------- test 4 ------------------------------------
mapbox::supercluster::Options options4;
options4.radius = 100;
options4.map = map;
Expand All @@ -141,4 +174,26 @@ int main() {
}
}
assert(actualVec1 == expectVec1);

// ----------------------- test 5 ------------------------------------
mapbox::supercluster::Options options5;
options5.minPoints = 5;
mapbox::supercluster::Supercluster index5(features, options5);

mapbox::feature::feature_collection<std::int16_t> tile5 = index5.getTile(0, 0, 0);
assert(tile5.size() == 49);

std::uint64_t num_points1 = 0;
for (auto &f : tile5) {
const auto itr = f.properties.find("cluster");
if (itr != f.properties.end() && itr->second.get<bool>()) {
const auto &point_count = f.properties["point_count"].get<std::uint64_t>();
assert(point_count >= 5);
num_points1 += point_count;
} else {
num_points1 += 1;
}
}

assert(num_points1 == 195);
}

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