Method MinMax

r/src/altrep.cpp:341–377

  template <bool Min>
  static SEXP MinMax(SEXP alt, Rboolean narm) {
    if (IsMaterialized(alt)) {
      return nullptr;
    }

    using data_type = typename std::conditional<sexp_type == REALSXP, double, int>::type;
    using scalar_type =
        typename std::conditional<sexp_type == INTSXP, Int32Scalar, DoubleScalar>::type;

    const auto& chunked_array = GetChunkedArray(alt);
    bool na_rm = narm == TRUE;
    auto n = chunked_array->length();
    auto null_count = chunked_array->null_count();
    if ((na_rm || n == 0) && null_count == n) {
      if (Min) {
        Rf_warning("no non-missing arguments to min; returning Inf");
        return Rf_ScalarReal(R_PosInf);
      } else {
        Rf_warning("no non-missing arguments to max; returning -Inf");
        return Rf_ScalarReal(R_NegInf);
      }
    }
    if (!na_rm && null_count > 0) {
      return cpp11::as_sexp(cpp11::na<data_type>());
    }

    auto options = NaRmOptions(na_rm);

    const auto& minmax = ValueOrStop(
        arrow::compute::CallFunction("min_max", {chunked_array}, options.get()));
    const auto& minmax_scalar =
        internal::checked_cast<const StructScalar&>(*minmax.scalar());

    const auto& result_scalar = internal::checked_cast<const scalar_type&>(
        *ValueOrStop(minmax_scalar.field(Min ? "min" : "max")));
    return cpp11::as_sexp(result_scalar.value);
  }

  static SEXP Min(SEXP alt, Rboolean narm) { return MinMax<true>(alt, narm); }