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92 lines
2.7 KiB
C++
92 lines
2.7 KiB
C++
#if !defined(ARCADIA_BUILD)
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# include "config_functions.h"
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#endif
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#if USE_H3
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#include <Columns/ColumnsNumber.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <Functions/FunctionFactory.h>
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#include <Functions/IFunction.h>
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#include <IO/WriteHelpers.h>
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#include <Common/typeid_cast.h>
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#include <ext/range.h>
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#include <constants.h>
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#include <h3api.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int ILLEGAL_TYPE_OF_ARGUMENT;
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extern const int ARGUMENT_OUT_OF_BOUND;
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}
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namespace
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{
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// Average metric edge length of H3 hexagon. The edge length `e` for given resolution `res` can
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// be used for converting metric search radius `radius` to hexagon search ring size `k` that is
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// used by `H3kRing` function. For small enough search area simple flat approximation can be used,
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// i.e. the smallest `k` that satisfies relation `3 k^2 - 3 k + 1 >= (radius / e)^2` should be
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// chosen
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class FunctionH3EdgeLengthM : public IFunction
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{
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public:
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static constexpr auto name = "h3EdgeLengthM";
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static FunctionPtr create(const Context &) { return std::make_shared<FunctionH3EdgeLengthM>(); }
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std::string getName() const override { return name; }
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size_t getNumberOfArguments() const override { return 1; }
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bool useDefaultImplementationForConstants() const override { return true; }
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DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
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{
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const auto * arg = arguments[0].get();
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if (!WhichDataType(arg).isUInt8())
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throw Exception(
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"Illegal type " + arg->getName() + " of argument " + std::to_string(1) + " of function " + getName() + ". Must be UInt8",
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ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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return std::make_shared<DataTypeFloat64>();
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}
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ColumnPtr executeImpl(ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
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{
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const auto * col_hindex = arguments[0].column.get();
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auto dst = ColumnVector<Float64>::create();
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auto & dst_data = dst->getData();
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dst_data.resize(input_rows_count);
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for (const auto row : ext::range(0, input_rows_count))
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{
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const UInt64 resolution = col_hindex->getUInt(row);
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if (resolution > MAX_H3_RES)
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throw Exception("The argument 'resolution' (" + toString(resolution) + ") of function " + getName()
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+ " is out of bounds because the maximum resolution in H3 library is " + toString(MAX_H3_RES), ErrorCodes::ARGUMENT_OUT_OF_BOUND);
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Float64 res = edgeLengthM(resolution);
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dst_data[row] = res;
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}
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return dst;
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}
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};
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}
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void registerFunctionH3EdgeLengthM(FunctionFactory & factory)
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{
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factory.registerFunction<FunctionH3EdgeLengthM>();
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}
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}
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#endif
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