Revert "Revert "Implement h3ToGeo function""

contrib/h3

@@ -1 +1 @@
-Subproject commit c7f46cfd71fb60e2fefc90e28abe81657deff735
+Subproject commit 5c44b06c406613b7792a60b11d04b871116f6e30

docs/en/sql-reference/functions/geo/h3.md

@@ -195,6 +195,41 @@ Result:
 └────────────────────┘
 ```
 
+## h3ToGeo {#h3togeo}
+
+Returns `(lon, lat)` that corresponds to the provided H3 index.
+
+**Syntax**
+
+``` sql
+h3ToGeo(h3Index)
+```
+
+**Arguments**
+
+-   `h3Index` — H3 Index. Type: [UInt64](../../../sql-reference/data-types/int-uint.md).
+
+**Returned values**
+
+-   `lon` — Longitude. Type: [Float64](../../../sql-reference/data-types/float.md).
+-   `lat` — Latitude. Type: [Float64](../../../sql-reference/data-types/float.md).
+
+
+**Example**
+
+Query:
+
+``` sql
+SELECT h3ToGeo(644325524701193974) coordinates;
+```
+
+Result:
+
+``` text
+┌─coordinates───────────────────────────┐
+│ (37.79506616830252,55.71290243145668) │
+└───────────────────────────────────────┘
+```
 ## h3kRing {#h3kring}
 
  Lists all the [H3](#h3index) hexagons in the raduis of `k` from the given hexagon in random order.

src/Functions/h3toGeo.cpp

@@ -0,0 +1,96 @@
+#if !defined(ARCADIA_BUILD)
+#    include "config_functions.h"
+#endif
+
+#if USE_H3
+
+#include <array>
+#include <math.h>
+#include <Columns/ColumnArray.h>
+#include <Columns/ColumnTuple.h>
+#include <Columns/ColumnsNumber.h>
+#include <DataTypes/DataTypeTuple.h>
+#include <DataTypes/DataTypesNumber.h>
+#include <Functions/FunctionFactory.h>
+#include <Functions/IFunction.h>
+#include <Common/typeid_cast.h>
+#include <ext/range.h>
+
+#include <h3api.h>
+
+
+namespace DB
+{
+namespace ErrorCodes
+{
+extern const int ILLEGAL_TYPE_OF_ARGUMENT;
+}
+
+namespace
+{
+
+/// Implements the function h3ToGeo which takes a single argument (h3Index)
+/// and returns the longitude and latitude that correspond to the provided h3 index
+class FunctionH3ToGeo : public IFunction
+{
+public:
+    static constexpr auto name = "h3ToGeo";
+
+    static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionH3ToGeo>(); }
+
+    std::string getName() const override { return name; }
+
+    size_t getNumberOfArguments() const override { return 1; }
+    bool useDefaultImplementationForConstants() const override { return true; }
+
+    DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
+    {
+        const auto * arg = arguments[0].get();
+        if (!WhichDataType(arg).isUInt64())
+            throw Exception(
+                "Illegal type " + arg->getName() + " of argument " + std::to_string(1) + " of function " + getName() + ". Must be UInt64",
+                ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
+
+        return std::make_shared<DataTypeTuple>(
+            DataTypes{std::make_shared<DataTypeFloat64>(), std::make_shared<DataTypeFloat64>()},
+            Strings{"longitude", "latitude"});
+    }
+
+    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
+    {
+        const auto * col_index = arguments[0].column.get();
+
+        auto latitude = ColumnFloat64::create(input_rows_count);
+        auto longitude = ColumnFloat64::create(input_rows_count);
+
+        ColumnFloat64::Container & lon_data = longitude->getData();
+        ColumnFloat64::Container & lat_data = latitude->getData();
+
+
+        for (size_t row = 0; row < input_rows_count; ++row)
+        {
+            H3Index h3index = col_index->getUInt(row);
+            GeoCoord coord{};
+
+            h3ToGeo(h3index,&coord);
+            lon_data[row] = radsToDegs(coord.lon);
+            lat_data[row] = radsToDegs(coord.lat);
+        }
+
+        MutableColumns columns;
+        columns.emplace_back(std::move(longitude));
+        columns.emplace_back(std::move(latitude));
+        return ColumnTuple::create(std::move(columns));
+    }
+};
+
+}
+
+void registerFunctionH3ToGeo(FunctionFactory & factory)
+{
+    factory.registerFunction<FunctionH3ToGeo>();
+}
+
+}
+
+#endif

src/Functions/registerFunctionsGeo.cpp

@@ -28,6 +28,7 @@ void registerFunctionSvg(FunctionFactory & factory);
 
 #if USE_H3
 void registerFunctionGeoToH3(FunctionFactory &);
+void registerFunctionH3ToGeo(FunctionFactory &);
 void registerFunctionH3EdgeAngle(FunctionFactory &);
 void registerFunctionH3EdgeLengthM(FunctionFactory &);
 void registerFunctionH3GetResolution(FunctionFactory &);
@@ -66,6 +67,7 @@ void registerFunctionsGeo(FunctionFactory & factory)
 
 #if USE_H3
     registerFunctionGeoToH3(factory);
+    registerFunctionH3ToGeo(factory);
     registerFunctionH3EdgeAngle(factory);
     registerFunctionH3EdgeLengthM(factory);
     registerFunctionH3GetResolution(factory);

tests/queries/0_stateless/01659_h3_buffer_overflow.sql

@@ -7,3 +7,4 @@ SELECT h3kRing(0xFFFFFFFFFFFFFF, 1000) FORMAT Null;
 SELECT h3GetBaseCell(0xFFFFFFFFFFFFFF) FORMAT Null;
 SELECT h3GetResolution(0xFFFFFFFFFFFFFF) FORMAT Null;
 SELECT h3kRing(0xFFFFFFFFFFFFFF, 10) FORMAT Null;
+SELECT h3ToGeo(0xFFFFFFFFFFFFFF) FORMAT Null;

tests/queries/0_stateless/01906_h3_to_geo.reference

@@ -0,0 +1,32 @@
+(-173.6412167681162,-14.130272474941535)
+(59.48137613600854,58.020407687755686)
+(172.68095885060296,-83.6576608516349)
+(-94.46556851304558,-69.1999982492279)
+(-8.188263637093279,-55.856179102736284)
+(77.25594891852249,47.39278564360122)
+(135.11348004704536,36.60778126579667)
+(39.28534828967223,49.07710003066973)
+(124.71163478198051,-27.481172161567258)
+(-147.4887686066785,76.73237945824442)
+(86.63291906118863,-25.52526285188784)
+(23.27751790712118,13.126101362212724)
+(-70.40163237204142,-63.12562536833242)
+(15.642428355535966,40.285813505163574)
+(-76.53411447979884,54.5560449693637)
+(8.19906334981474,67.69370966550179)
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok
+ok

tests/queries/0_stateless/01906_h3_to_geo.sql

@@ -0,0 +1,61 @@
+DROP TABLE IF EXISTS h3_indexes;
+
+CREATE TABLE h3_indexes (h3_index UInt64) ENGINE = Memory;
+
+-- Random geo coordinates were generated using the H3 tool: https://github.com/ClickHouse-Extras/h3/blob/master/src/apps/testapps/mkRandGeo.c at various resolutions from 0 to 15.
+-- Corresponding H3 index values were in turn generated with those geo coordinates using `geoToH3(lon, lat, res)` ClickHouse function for the following test.
+
+INSERT INTO h3_indexes VALUES (579205133326352383);
+INSERT INTO h3_indexes VALUES (581263419093549055);
+INSERT INTO h3_indexes VALUES (589753847883235327);
+INSERT INTO h3_indexes VALUES (594082350283882495);
+INSERT INTO h3_indexes VALUES (598372386957426687);
+INSERT INTO h3_indexes VALUES (599542359671177215);
+INSERT INTO h3_indexes VALUES (604296355086598143);
+INSERT INTO h3_indexes VALUES (608785214872748031);
+INSERT INTO h3_indexes VALUES (615732192485572607);
+INSERT INTO h3_indexes VALUES (617056794467368959);
+INSERT INTO h3_indexes VALUES (624586477873168383);
+INSERT INTO h3_indexes VALUES (627882919484481535);
+INSERT INTO h3_indexes VALUES (634600058503392255);
+INSERT INTO h3_indexes VALUES (635544851677385791);
+INSERT INTO h3_indexes VALUES (639763125756281263);
+INSERT INTO h3_indexes VALUES (644178757620501158);
+
+
+SELECT h3ToGeo(h3_index) FROM h3_indexes ORDER BY h3_index;
+
+DROP TABLE h3_indexes;
+
+DROP TABLE IF EXISTS h3_geo;
+
+-- compare if the results of h3ToGeo and geoToH3 are the same
+
+CREATE TABLE h3_geo(lat Float64, lon Float64, res UInt8) ENGINE = Memory;
+
+INSERT INTO h3_geo VALUES (-173.6412167681162, -14.130272474941535, 0);
+INSERT INTO h3_geo VALUES (59.48137613600854, 58.020407687755686, 1);
+INSERT INTO h3_geo VALUES (172.68095885060296, -83.6576608516349, 2);
+INSERT INTO h3_geo VALUES (-94.46556851304558, -69.1999982492279, 3);
+INSERT INTO h3_geo VALUES (-8.188263637093279, -55.856179102736284, 4);
+INSERT INTO h3_geo VALUES (77.25594891852249, 47.39278564360122, 5);
+INSERT INTO h3_geo VALUES (135.11348004704536, 36.60778126579667, 6);
+INSERT INTO h3_geo VALUES (39.28534828967223, 49.07710003066973, 7);
+INSERT INTO h3_geo VALUES (124.71163478198051, -27.481172161567258, 8);
+INSERT INTO h3_geo VALUES (-147.4887686066785, 76.73237945824442, 9);
+INSERT INTO h3_geo VALUES (86.63291906118863, -25.52526285188784, 10);
+INSERT INTO h3_geo VALUES (23.27751790712118, 13.126101362212724, 11);
+INSERT INTO h3_geo VALUES (-70.40163237204142, -63.12562536833242, 12);
+INSERT INTO h3_geo VALUES (15.642428355535966, 40.285813505163574, 13);
+INSERT INTO h3_geo VALUES (-76.53411447979884, 54.5560449693637, 14);
+INSERT INTO h3_geo VALUES (8.19906334981474, 67.69370966550179, 15);
+
+SELECT result FROM (
+    SELECT
+        (lat, lon) AS input_geo,
+        h3ToGeo(geoToH3(lat, lon, res)) AS output_geo,
+        if(input_geo = output_geo, 'ok', 'fail') AS result
+    FROM h3_geo
+);
+
+DROP TABLE h3_geo;