Match variable string input

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 = {