1 | #include "config_functions.h" |
---|---|
2 | #if USE_H3 |
3 | # include <Columns/ColumnsNumber.h> |
4 | # include <DataTypes/DataTypesNumber.h> |
5 | # include <Functions/FunctionFactory.h> |
6 | # include <Functions/IFunction.h> |
7 | # include <Common/typeid_cast.h> |
8 | # include <ext/range.h> |
9 | |
10 | # include <h3api.h> |
11 | |
12 | |
13 | namespace DB |
14 | { |
15 | // Average metric edge length of H3 hexagon. The edge length `e` for given resolution `res` can |
16 | // be used for converting metric search radius `radius` to hexagon search ring size `k` that is |
17 | // used by `H3kRing` function. For small enough search area simple flat approximation can be used, |
18 | // i.e. the smallest `k` that satisfies relation `3 k^2 - 3 k + 1 >= (radius / e)^2` should be |
19 | // chosen |
20 | class FunctionH3EdgeLengthM : public IFunction |
21 | { |
22 | public: |
23 | static constexpr auto name = "h3EdgeLengthM"; |
24 | |
25 | static FunctionPtr create(const Context &) { return std::make_shared<FunctionH3EdgeLengthM>(); } |
26 | |
27 | std::string getName() const override { return name; } |
28 | |
29 | size_t getNumberOfArguments() const override { return 1; } |
30 | bool useDefaultImplementationForConstants() const override { return true; } |
31 | |
32 | DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override |
33 | { |
34 | auto arg = arguments[0].get(); |
35 | if (!WhichDataType(arg).isUInt8()) |
36 | throw Exception( |
37 | "Illegal type "+ arg->getName() + " of argument "+ std::to_string(1) + " of function "+ getName() + ". Must be UInt8", |
38 | ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT); |
39 | |
40 | return std::make_shared<DataTypeFloat64>(); |
41 | } |
42 | |
43 | void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) override |
44 | { |
45 | const auto col_hindex = block.getByPosition(arguments[0]).column.get(); |
46 | |
47 | auto dst = ColumnVector<Float64>::create(); |
48 | auto & dst_data = dst->getData(); |
49 | dst_data.resize(input_rows_count); |
50 | |
51 | for (const auto row : ext::range(0, input_rows_count)) |
52 | { |
53 | const int resolution = col_hindex->getUInt(row); |
54 | |
55 | Float64 res = edgeLengthM(resolution); |
56 | |
57 | dst_data[row] = res; |
58 | } |
59 | |
60 | block.getByPosition(result).column = std::move(dst); |
61 | } |
62 | }; |
63 | |
64 | |
65 | void registerFunctionH3EdgeLengthM(FunctionFactory & factory) |
66 | { |
67 | factory.registerFunction<FunctionH3EdgeLengthM>(); |
68 | } |
69 | |
70 | } |
71 | #endif |
72 |