ClickHouse

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#include <DataTypes/DataTypesNumber.h>
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#include <Columns/ColumnsNumber.h>
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#include <Columns/ColumnConst.h>
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#include <Common/typeid_cast.h>
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#include <Common/assert_cast.h>
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#include <Functions/IFunction.h>
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#include <Functions/FunctionHelpers.h>
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#include <Functions/FunctionFactory.h>
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#include <base/range.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 TOO_MANY_ARGUMENTS_FOR_FUNCTION;
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    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
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    extern const int ILLEGAL_COLUMN;
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}
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namespace
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{
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/**
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 * The function checks if a point is in one of ellipses in set.
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 * The number of arguments must be 2 + 4*N where N is the number of ellipses.
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 * The arguments must be arranged as follows: (x, y, x_0, y_0, a_0, b_0, ..., x_i, y_i, a_i, b_i)
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 * All ellipses parameters must be const values;
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 *
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 * The function first checks bounding box condition.
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 * If a point is inside an ellipse's bounding box, the quadratic condition is evaluated.
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 *
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 * Here we assume that points in one columns are close and are likely to fit in one ellipse,
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 * so the last success ellipse index is remembered to check this ellipse first for next point.
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 *
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 */
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class FunctionPointInEllipses : public IFunction
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{
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public:
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    static constexpr auto name = "pointInEllipses";
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    static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionPointInEllipses>(); }
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private:
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    struct Ellipse
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    {
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        Float64 x;
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        Float64 y;
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        Float64 a;
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        Float64 b;
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    };
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    String getName() const override { return name; }
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    bool isVariadic() const override { return true; }
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    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return true; }
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    size_t getNumberOfArguments() const override { return 0; }
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    DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
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    {
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        if (arguments.size() < 6 || arguments.size() % 4 != 2)
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        {
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            throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
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                "Incorrect number of arguments of function {}. "
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                "Must be 2 for your point plus 4 * N for ellipses (x_i, y_i, a_i, b_i).", getName());
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        }
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        /// For array on stack, see below.
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        if (arguments.size() > 10000)
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        {
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            throw Exception(ErrorCodes::TOO_MANY_ARGUMENTS_FOR_FUNCTION,
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                            "Number of arguments of function {} is too large (maximum: 10000).",
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                            getName());
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        }
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        for (const auto arg_idx : collections::range(0, arguments.size()))
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        {
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            const auto * arg = arguments[arg_idx].get();
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            if (!WhichDataType(arg).isFloat64())
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            {
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                throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type {} of argument {} of function {}. "
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                    "Must be Float64", arg->getName(), std::to_string(arg_idx + 1), getName());
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            }
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        }
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        return std::make_shared<DataTypeUInt8>();
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    }
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    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
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    {
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        const auto size = input_rows_count;
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        /// Prepare array of ellipses.
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        size_t ellipses_count = (arguments.size() - 2) / 4;
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        std::vector<Ellipse> ellipses(ellipses_count);
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        for (const auto ellipse_idx : collections::range(0, ellipses_count))
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        {
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            Float64 ellipse_data[4];
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            for (const auto idx : collections::range(0, 4))
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            {
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                size_t arg_idx = 2 + 4 * ellipse_idx + idx;
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                const auto * column = arguments[arg_idx].column.get();
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                if (const auto * col = checkAndGetColumnConst<ColumnVector<Float64>>(column))
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                {
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                    ellipse_data[idx] = col->getValue<Float64>();
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                }
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                else
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                {
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                    throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type {} of argument {} of function {}. "
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                        "Must be const Float64", column->getName(), std::to_string(arg_idx + 1), getName());
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                }
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            }
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            ellipses[ellipse_idx] = Ellipse{ellipse_data[0], ellipse_data[1], ellipse_data[2], ellipse_data[3]};
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        }
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        int const_cnt = 0;
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        for (const auto idx : collections::range(0, 2))
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        {
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            const auto * column = arguments[idx].column.get();
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            if (typeid_cast<const ColumnConst *> (column))
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            {
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                ++const_cnt;
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            }
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            else if (!typeid_cast<const ColumnVector<Float64> *> (column))
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            {
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                throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Illegal column {} of argument of function {}",
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                    column->getName(), getName());
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            }
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        }
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        const auto * col_x = arguments[0].column.get();
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        const auto * col_y = arguments[1].column.get();
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        if (const_cnt == 0)
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        {
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                const auto * col_vec_x = assert_cast<const ColumnVector<Float64> *> (col_x);
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                const auto * col_vec_y = assert_cast<const ColumnVector<Float64> *> (col_y);
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                auto dst = ColumnVector<UInt8>::create();
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                auto & dst_data = dst->getData();
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                dst_data.resize(size);
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                size_t start_index = 0;
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                for (const auto row : collections::range(0, size))
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                {
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                    dst_data[row] = isPointInEllipses(col_vec_x->getData()[row], col_vec_y->getData()[row], ellipses.data(), ellipses_count, start_index);
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                }
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                return dst;
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        }
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        else if (const_cnt == 2)
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        {
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            const auto * col_const_x = assert_cast<const ColumnConst *> (col_x);
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            const auto * col_const_y = assert_cast<const ColumnConst *> (col_y);
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            size_t start_index = 0;
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            UInt8 res = isPointInEllipses(col_const_x->getValue<Float64>(), col_const_y->getValue<Float64>(), ellipses.data(), ellipses_count, start_index);
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            return DataTypeUInt8().createColumnConst(size, res);
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        }
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        else
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        {
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            throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal types {}, {} of arguments 1, 2 of function {}. "
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                "Both must be either const or vector", col_x->getName(), col_y->getName(), getName());
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        }
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    }
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    static bool isPointInEllipses(Float64 x, Float64 y, const Ellipse * ellipses, size_t ellipses_count, size_t & start_index)
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    {
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        size_t index = 0 + start_index;
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        for (size_t i = 0; i < ellipses_count; ++i)
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        {
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            Ellipse el = ellipses[index];
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            double p1 = ((x - el.x) / el.a);
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            double p2 = ((y - el.y) / el.b);
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            if (x <= el.x + el.a && x >= el.x - el.a && y <= el.y + el.b && y >= el.y - el.b /// Bounding box check
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                && p1 * p1 + p2 * p2 <= 1.0)    /// Precise check
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            {
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                start_index = index;
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                return true;
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            }
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            ++index;
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            if (index == ellipses_count)
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            {
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                index = 0;
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            }
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        }
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        return false;
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    }
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};
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}
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REGISTER_FUNCTION(PointInEllipses)
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{
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    factory.registerFunction<FunctionPointInEllipses>();
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}
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}
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