08 - Logical Functions with Missing Values

1 Notes

• These functions ignore NA values for now. Adjustments for handling NA values are covered in a separate vignette.
• R already provides efficient versions of the functions covered here. This is just to illustrate how to use C++ code.

2 Is any value in a vector ‘true’?

The following function expands the previous any_cpp() function to handle missing values.

[[cpp4r::register]]
bool any2_cpp(logicals x, bool na_rm = false) {
  int n = x.size();
  bool has_na = false;
  
  for (int i = 0; i < n; ++i) {
    if (x[i] == NA_LOGICAL) {
      has_na = true;
      if (!na_rm) {
        continue; // Skip NA values if na_rm is false
      }
    } else if (x[i]) {
      return true;
    }
  }
  
  // If we found any NA and na_rm is false, return NA
  if (has_na && !na_rm) {
    return NA_LOGICAL;
  }
  
  return false;
}

Benchmark the functions as in the “Logical Functions” and “Rolling Functions” vignettes.

3 Which elements in a vector are ‘true’?

The following function expands the previous which_cpp() function to handle missing values.

[[cpp4r::register]]
integers which2_cpp(logicals x, bool na_rm = false) {
  int n = x.size();
  writable::integers res;
  int j = 0;

  for (int i = 0; i < n; ++i) {
    if (x[i] == NA_LOGICAL) {
      if (!na_rm) {
        // Skip NA values if na_rm is false
        continue;
      }
    } else if (x[i]) {
      ++j;
      res.push_back(i + 1);
    }
  }

  if (j == 0) {
    return integers(0);
  } else {
    return res;
  }
}

Benchmark the functions as in the “Logical Functions” and “Rolling Functions” vignettes.

4 Are all values in a vector ‘true’?

The following function expands the previous all_cpp() function to handle missing values.

[[cpp4r::register]]
bool all2_cpp_1(logicals x, bool na_rm = false) {
  int n = x.size();
  bool has_na = false;
  
  for (int i = 0; i < n; ++i) {
    if (x[i] == NA_LOGICAL) {
      has_na = true;
      if (!na_rm) {
        continue; // Skip NA values if na_rm is false
      }
    } else if (!x[i]) {
      return false;
    }
  }
  
  // If we found any NA and na_rm is false, return NA
  if (has_na && !na_rm) {
    return NA_LOGICAL;
  }
  
  return true;
}

More concise C++ alternatives are:

[[cpp4r::register]]
bool all2_cpp_2(logicals x, bool na_rm = false) {
  bool has_na = false;
  
  for (int i = 0; i < x.size(); ++i) {
    if (x[i] == NA_LOGICAL) {
      has_na = true;
      if (!na_rm) {
        continue;
      }
    } else if (!x[i]) {
      return false;
    }
  }
  
  if (has_na && !na_rm) {
    return NA_LOGICAL;
  }
  
  return true;
}

[[cpp4r::register]]
bool all2_cpp_3(logicals x, bool na_rm = false) {
  bool has_na = false;
  
  for (int i = 0; i < x.size(); ++i) {
    if (x[i] == NA_LOGICAL) {
      has_na = true;
      if (!na_rm) {
        continue;
      }
    } else if (!x[i]) {
      return false;
    }
  }
  
  if (has_na && !na_rm) {
    return NA_LOGICAL;
  }
  
  return true;
}

Benchmark the functions as in the “Logical Functions” and “Rolling Functions” vignettes.