add option for realization selection: first only realization

pcmdi_metrics/mean_climate/mean_climate_driver.py

@@ -20,6 +20,7 @@
  mean_climate_metrics_to_json,
 )
 from pcmdi_metrics.variability_mode.lib import tree
+from pcmdi_metrics.variability_mode.lib import sort_human
 
 
 parser = create_mean_climate_parser()
@@ -59,13 +60,16 @@
 diagnostics_output_path = diagnostics_output_path.replace('%(case_id)', case_id)
 
 find_all_realizations = False
+first_realization_only = False
 if realization is None:
  realization = ""
  realizations = [realization]
 elif isinstance(realization, str):
  if realization.lower() in ["all", "*"]:
  find_all_realizations = True
  realizations = "Search for all realizations!!"
+ elif realization.lower() in ["first", "first_only"]:
+ first_realization_only = True
  else:
  realizations = [realization]
 
@@ -206,7 +210,7 @@
 
  result_dict["RESULTS"][model][ref]["source"] = ref_dataset_name 
 
- if find_all_realizations:
+ if find_all_realizations or first_realization_only:
  test_data_full_path = os.path.join(
  test_data_path,
  filename_template).replace('%(variable)', varname).replace('%(model)', model).replace('%(model_version)', model).replace('%(realization)', '*')
@@ -215,6 +219,9 @@
  realizations = []
  for ncfile in ncfiles:
  realizations.append(ncfile.split('/')[-1].split('.')[3])
+ realizations = sort_human(realizations)
+ if first_realization_only:
+ realizations == realizations[0:1]
  print('realizations (after search): ', realizations)
 
  for run in realizations: