IodaGroupIndices.cc

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/*
 * (C) Copyright 2021 UCAR
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 */
 
#include "ufo/utils/IodaGroupIndices.h"
 
#include "eckit/exception/Exceptions.h"
#include "ioda/ObsGroup.h"
#include "oops/base/Variables.h"
 
namespace ufo {
 
// -----------------------------------------------------------------------------
/// Returns indices of all elements in the range
/// [\p elements_to_look_for_begin, \p elements_to_look_for_end) in the \p all_elements vector,
/// in the same order that the former are in.
/// Throws an exception if at least one of elements looked for is missing
/// from \p all_elements.
template<typename T>
std::vector<int> getAllIndices(const std::vector<T> & all_elements,
                               typename std::vector<T>::const_iterator elements_to_look_for_begin,
                               typename std::vector<T>::const_iterator elements_to_look_for_end) {
  std::vector<int> result;
  for (typename std::vector<T>::const_iterator sought_it = elements_to_look_for_begin;
       sought_it != elements_to_look_for_end; ++sought_it) {
    const T &sought = *sought_it;
    const auto found_it = std::find(all_elements.begin(), all_elements.end(), sought);
    if (found_it != all_elements.end()) {
      result.push_back(std::distance(all_elements.begin(), found_it));
    } else {
      const std::string errormsg = "getAllIndices: Can't find element in the vector";
      throw eckit::BadParameter(errormsg, Here());
    }
  }
  return result;
}
 
// -----------------------------------------------------------------------------
/// Returns indices of all elements in \p elements_to_look_for in the \p all_elements vector,
/// in the same order that \p elements_to_look_for are in.
/// Throws an exception if at least one of elements looked for is missing
/// from \p all_elements.
template<typename T>
std::vector<int> getAllIndices(const std::vector<T> & all_elements,
                               const std::vector<T> & elements_to_look_for) {
  return getAllIndices(all_elements, elements_to_look_for.begin(), elements_to_look_for.end());
}
 
// -----------------------------------------------------------------------------
std::vector<int> getRequiredVariableIndices(const ioda::ObsGroup &obsgroup,
                 const std::string &varname,
                 typename std::vector<std::string>::const_iterator elements_to_look_for_begin,
                 typename std::vector<std::string>::const_iterator elements_to_look_for_end) {
  ioda::Variable var = obsgroup.vars.open(varname);
  std::vector<std::string> elements_in_group;
  var.read<std::string>(elements_in_group);
  return getAllIndices(elements_in_group, elements_to_look_for_begin, elements_to_look_for_end);
}
 
// -----------------------------------------------------------------------------
 
std::vector<int> getRequiredVarOrChannelIndices(const ioda::ObsGroup &obsgroup,
                                                const oops::Variables &vars_to_look_for) {
  if (vars_to_look_for.channels().empty()) {
    // Read all variables from the file into std vector
    ioda::Variable variablesvar = obsgroup.vars.open("variables");
    std::vector<std::string> variables;
    variablesvar.read<std::string>(variables);
 
    // Find the indices of the ones we need
    return getAllIndices(variables, vars_to_look_for.variables());
  } else {
    // At present this function can search either for channel numbers or variable names,
    // but not both. So make sure there's only one multi-channel variable.
    ASSERT(vars_to_look_for.variables().size() == vars_to_look_for.channels().size());
 
    // Read all channels from the file into std vector
    ioda::Variable channelsvar = obsgroup.vars.open("channels");
    std::vector<int> channels;
    channelsvar.read<int>(channels);
 
    // Find the indices of the ones we need
    return getAllIndices(channels, vars_to_look_for.channels());
  }
}
 
// -----------------------------------------------------------------------------
 
}  // namespace ufo