From dcb26f56acd0f1dbb9104f590955dd7104b22db8 Mon Sep 17 00:00:00 2001
From: Jared Lewis <jared@jared.kiwi.nz>
Date: Tue, 17 Dec 2024 16:14:07 +1100
Subject: [PATCH 1/2] fix: Handle none values

---
 packages/ref/src/ref/datasets/cmip6.py        | 15 +++++-----
 .../ref/tests/unit/datasets/test_cmip6.py     | 28 ++++++++++++++++++-
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/packages/ref/src/ref/datasets/cmip6.py b/packages/ref/src/ref/datasets/cmip6.py
index 433639e..90a6e94 100644
--- a/packages/ref/src/ref/datasets/cmip6.py
+++ b/packages/ref/src/ref/datasets/cmip6.py
@@ -52,17 +52,18 @@ def _fix_parent_variant_label(group: pd.DataFrame) -> pd.DataFrame:
 
     data_catalog = data_catalog.groupby("instance_id").apply(_fix_parent_variant_label).reset_index(drop=True)
 
-    # EC-Earth3 uses "D" as a suffix for the branch_time_in_child and branch_time_in_parent columns
-    data_catalog["branch_time_in_child"] = pd.to_numeric(
-        data_catalog["branch_time_in_child"].astype(str).str.replace("D", ""), errors="raise"
-    )
-    data_catalog["branch_time_in_parent"] = pd.to_numeric(
-        data_catalog["branch_time_in_parent"].astype(str).str.replace("D", ""), errors="raise"
-    )
+    data_catalog["branch_time_in_child"] = _clean_branch_time(data_catalog["branch_time_in_child"])
+    data_catalog["branch_time_in_parent"] = _clean_branch_time(data_catalog["branch_time_in_parent"])
 
     return data_catalog
 
 
+def _clean_branch_time(branch_time: pd.Series[str]) -> pd.Series[float]:
+    # EC-Earth3 uses "D" as a suffix for the branch_time_in_child and branch_time_in_parent columns
+    # Handle missing values (these result in nan values)
+    return pd.to_numeric(branch_time.astype(str).str.replace("D", "").replace("None", ""), errors="raise")
+
+
 class CMIP6DatasetAdapter(DatasetAdapter):
     """
     Adapter for CMIP6 datasets
diff --git a/packages/ref/tests/unit/datasets/test_cmip6.py b/packages/ref/tests/unit/datasets/test_cmip6.py
index 5899a5d..ba5583b 100644
--- a/packages/ref/tests/unit/datasets/test_cmip6.py
+++ b/packages/ref/tests/unit/datasets/test_cmip6.py
@@ -1,9 +1,10 @@
 import datetime
 
+import numpy as np
 import pandas as pd
 import pytest
 
-from ref.datasets.cmip6 import CMIP6DatasetAdapter, _parse_datetime
+from ref.datasets.cmip6 import CMIP6DatasetAdapter, _apply_fixes, _parse_datetime
 
 
 @pytest.fixture
@@ -76,3 +77,28 @@ def test_load_local_datasets(self, esgf_data_dir, catalog_regression):
         catalog_regression(
             data_catalog.sort_values(["instance_id", "start_time"]), basename="cmip6_catalog_local"
         )
+
+
+def test_apply_fixes():
+    df = pd.DataFrame(
+        {
+            "instance_id": ["dataset_001", "dataset_001", "dataset_002"],
+            "parent_variant_label": ["r1i1p1f1", "r1i1p1f2", "r1i1p1f2"],
+            "variant_label": ["r1i1p1f1", "r1i1p1f1", "r1i1p1f2"],
+            "branch_time_in_child": ["0D", "12", "12.0"],
+            "branch_time_in_parent": [None, "12", "12.0"],
+        }
+    )
+
+    res = _apply_fixes(df)
+
+    exp = pd.DataFrame(
+        {
+            "instance_id": ["dataset_001", "dataset_001", "dataset_002"],
+            "parent_variant_label": ["r1i1p1f1", "r1i1p1f1", "r1i1p1f2"],
+            "variant_label": ["r1i1p1f1", "r1i1p1f1", "r1i1p1f2"],
+            "branch_time_in_child": [0.0, 12.0, 12.0],
+            "branch_time_in_parent": [np.nan, 12.0, 12.0],
+        }
+    )
+    pd.testing.assert_frame_equal(res, exp)

From 508c1f46dca9c2e15c0622a387316d40d076684c Mon Sep 17 00:00:00 2001
From: Jared Lewis <jared@jared.kiwi.nz>
Date: Tue, 17 Dec 2024 16:16:04 +1100
Subject: [PATCH 2/2] docs: Changelog

---
 changelog/42.fix.md | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 changelog/42.fix.md

diff --git a/changelog/42.fix.md b/changelog/42.fix.md
new file mode 100644
index 0000000..137575f
--- /dev/null
+++ b/changelog/42.fix.md
@@ -0,0 +1,2 @@
+Handle missing branch times.
+Fixes [#38](https://github.com/CMIP-REF/cmip-ref/issues/38).