BYearBegin

class pandas::BYearBegin

pandas C++ class.

Example

#include <pandas/pandas.h>
using namespace pandas;

// Use BYearBegin
BYearBegin obj;
// ... operations ...

Aggregation

Signature	Return Type	Location	Example
numpy::datetime64 apply(const numpy::datetime64& dt) const override	numpy::datetime64	pd_dateoffset.h:1504	View

Type Checking

Signature	Return Type	Location	Example
bool is_calendar_offset() const override	bool	pd_dateoffset.h:1490
bool is_on_offset(const numpy::datetime64& dt) const override	bool	pd_dateoffset.h:1541	View

Other Methods

Signature	Return Type	Location	Example
std::string freqstr() const override	std::string	pd_dateoffset.h:1493	View
int month() const	int	pd_dateoffset.h:1489	View
std::string name() const override { return freqstr()	std::string	pd_dateoffset.h:1496	View
std::string repr() const override	std::string	pd_dateoffset.h:1497	View
int64_t total_nanoseconds() const override	int64_t	pd_dateoffset.h:1491

Code Examples

The following examples are extracted from the test suite.

apply (pd_test_1_all.cpp:11244)

        void pd_test_func_apply_dataframe_apply_axis0() {
            std::cout << "========= DataFrame apply axis=0 ======================";

            std::map<std::string, std::vector<double>> data = {
                {"A", {1.0, 2.0, 3.0}},
                {"B", {4.0, 5.0, 6.0}}
            };
            pandas::DataFrame df(data);

            // apply axis=0 applies function to each column
            auto result = df.apply([](const std::vector<double>& col) {
                return std::accumulate(col.begin(), col.end(), 0.0);
            }, 0);

            bool passed = true;

            // Plan F·dtype: axis=0 reduce now returns a single "result" column
            // with the original column names ("A", "B") as the row index.
            // Sum of A: 1+2+3=6, Sum of B: 4+5+6=15
            const auto& result_col = result["result"];
            double sum_a = std::stod(result_col.get_value_str(0));

is_on_offset (pd_test_3_all.cpp:18263)

void pd_test_business_day_offset() {
    std::cout << "========= BusinessDay offset ===========================";

    pandas::BusinessDay offset(1);
    if (offset.freqstr() != "B") {
        std::cout << "  [FAIL] : BusinessDay freqstr() failed" << std::endl;
        throw std::runtime_error("pd_test_business_day_offset: freqstr() failed");
    }

    // Test is_on_offset (Friday = weekday)
    numpy::datetime64 friday("2020-01-17");  // Friday
    if (!offset.is_on_offset(friday)) {
        std::cout << "  [FAIL] : BusinessDay is_on_offset(Friday) failed" << std::endl;
        throw std::runtime_error("pd_test_business_day_offset: is_on_offset(Friday) failed");
    }

    // Test is_on_offset (Saturday = weekend)
    numpy::datetime64 saturday("2020-01-18");  // Saturday
    if (offset.is_on_offset(saturday)) {
        std::cout << "  [FAIL] : BusinessDay is_on_offset(Saturday) should be false" << std::endl;

freqstr (pd_test_1_all.cpp:2671)

        }

        pandas::PeriodDtype dtype_y("Y");
        if (dtype_y.name() != "period[Y]") {
            std::cout << "  [FAIL] : dtype_y.name() should be 'period[Y]'" << std::endl;
            throw std::runtime_error("pd_test_period_array_freq_validation failed: dtype name Y");
        }

        // Test frequency string
        pandas::PeriodArray arr(std::vector<std::string>{"2024-01-15"}, "D");
        if (arr.freqstr() != "D") {
            std::cout << "  [FAIL] : arr.freqstr() should be 'D'" << std::endl;
            throw std::runtime_error("pd_test_period_array_freq_validation failed: freqstr");
        }

        std::cout << " -> tests passed" << std::endl;
    }

    void pd_test_period_array_year_month_quarter() {
        std::cout << "========= PeriodArray: year/month/quarter components ======================= ";

month (pd_test_1_all.cpp:1180)

    void pd_test_datetime_array_component_month_day() {
        std::cout << "========= DatetimeArray: month/day components ======================= ";

        pandas::DatetimeArray arr(std::vector<std::string>{
            "2023-03-15",
            "2023-12-25",
            "NaT"
        });

        // Month
        auto months = arr.month();
        auto m0 = months[0];
        if (!m0.has_value() || m0.value() != 3) {
            std::cout << "  [FAIL] : month[0] should be 3" << std::endl;
            throw std::runtime_error("pd_test_datetime_array_component_month_day failed: month[0]");
        }
        auto m1 = months[1];
        if (!m1.has_value() || m1.value() != 12) {
            std::cout << "  [FAIL] : month[1] should be 12" << std::endl;
            throw std::runtime_error("pd_test_datetime_array_component_month_day failed: month[1]");
        }

name (pd_test_1_all.cpp:295)

            throw std::runtime_error("pd_test_boolean_array_reductions failed: mean");
        }

        std::cout << " -> tests passed" << std::endl;
    }

    void pd_test_boolean_array_dtype() {
        std::cout << "========= BooleanArray: dtype ======================= ";

        pandas::BooleanArray arr;
        if (arr.dtype().name() != "boolean") {
            std::cout << "  [FAIL] : in pd_test_boolean_array_dtype() : dtype name should be 'boolean'" << std::endl;
            throw std::runtime_error("pd_test_boolean_array_dtype failed: dtype name");
        }

        if (arr.dtype().kind() != "b") {
            std::cout << "  [FAIL] : in pd_test_boolean_array_dtype() : dtype kind should be 'b'" << std::endl;
            throw std::runtime_error("pd_test_boolean_array_dtype failed: dtype kind");
        }

        std::cout << " -> tests passed" << std::endl;

repr (pd_test_1_all.cpp:10906)

    std::cout << " -> tests passed" << std::endl;
}

void pd_test_extension_index_repr() {
    std::cout << "========= repr =========================";

    pandas::CategoricalArray arr({"a", "b", "c"});
    // Use ExtensionIndex<CategoricalArray> directly to test base class repr
    pandas::ExtensionIndex<pandas::CategoricalArray> idx(arr, "test");

    std::string repr_str = idx.repr();

    bool passed = (!repr_str.empty() && repr_str.find("ExtensionIndex") != std::string::npos);
    if (!passed) {
        std::cout << "  [FAIL] : in pd_test_extension_index_repr() : repr check failed" << std::endl;
        throw std::runtime_error("pd_test_extension_index_repr failed");
    }

    std::cout << " -> tests passed" << std::endl;
}