Match variable string input (#245)

* Add failing test

* manual addition

* final test

* fix the test

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update whats-new.rst

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

cmip6_preprocessing/postprocessing.py

@@ -5,7 +5,11 @@
 import numpy as np
 import xarray as xr
 
-from cmip6_preprocessing.utils import _key_from_attrs, cmip6_dataset_id
+from cmip6_preprocessing.utils import (
+ _key_from_attrs,
+ _maybe_make_list,
+ cmip6_dataset_id,
+)
 
 
 try:
@@ -604,6 +608,8 @@ def match_metrics(
  # metrics should never match the variable
  exact_attrs_wo_var = [ma for ma in exact_attrs if ma != "variable_id"]
 
+ match_variables = _maybe_make_list(match_variables)
+
  # if match is set to exact check all these attributes
  if match_attrs == "exact":
  match_attrs = exact_attrs_wo_var

docs/whats-new.rst

@@ -25,6 +25,8 @@ By `Tom Nicholas <https://github.com/TomNicholas>`_ and `Julius Busecke <https:/
 
 Bugfixes
 ~~~~~~~~
+- :py:func:`~cmip6_preprocessing.postprocessing.match_metrics` now accepts single variables as str input (:issue:`229`, :pull:`245`)
+
 - :py:func:`~cmip6_preprocessing.postprocessing.concat_members` now returns a dataset with labelled `member_id` dimension (:issue:`196` , :pull:`197`). By `Julius Busecke <https://github.com/jbusecke>`_
 
 - Fixes incompatibility with upstream changes in xarray>=0.19.0 (:issue:`173`, :pull:`174`). By `Julius Busecke <https://github.com/jbusecke>`_

tests/test_postprocessing.py

@@ -357,6 +357,27 @@ def test_match_metrics_print_statistics(capsys, metricname):
  assert "No match found:" + str({metricname: 0}) in captured.out
 
 
+def test_match_metrics_match_variable_str_input():
+ # give a dataset that has member_id as dim (indicator that it was aggregated).
+ metricname = "area"
+ attrs = {
+ "source_id": "a",
+ "grid_label": "a",
+ "experiment_id": "a",
+ "table_id": "a",
+ "variant_label": "a",
+ "version": "a",
+ }
+ ds = random_ds()
+ ds.attrs = attrs
+ ds_metric = random_ds().rename({"data": metricname})
+ ds_metric.attrs = attrs
+
+ ds_dict_parsed_list = match_metrics({"a": ds}, {"aa": ds_metric}, [metricname])
+ ds_dict_parsed_str = match_metrics({"a": ds}, {"aa": ds_metric}, metricname)
+ xr.testing.assert_equal(ds_dict_parsed_str["a"], ds_dict_parsed_list["a"])
+
+
 @pytest.mark.parametrize("combine_func_kwargs", [{}, {"compat": "override"}])
 def test_combine_datasets_merge(combine_func_kwargs):
  attrs_a = {