From 52c43287821a6f3470fa42e56b42919b4d4ee0b9 Mon Sep 17 00:00:00 2001
From: Paul Natsuo Kishimoto <mail@paul.kishimoto.name>
Date: Wed, 30 Aug 2023 20:04:47 +0200
Subject: [PATCH] Address FutureWarnings from pandas 2.1.0

---
 genno/core/attrseries.py        | 4 ++--
 genno/tests/compat/test_pyam.py | 5 +++++
 genno/util.py                   | 7 +++++++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/genno/core/attrseries.py b/genno/core/attrseries.py
index 541a4846..7ece6097 100644
--- a/genno/core/attrseries.py
+++ b/genno/core/attrseries.py
@@ -186,7 +186,7 @@ def bfill(self, dim: Hashable, limit: Optional[int] = None):
         #      if needed use _maybe_groupby()
         return self._replace(
             self.unstack(dim)
-            .fillna(method="bfill", axis=1, limit=limit)
+            .bfill(axis=1, limit=limit)
             .stack()
             .reorder_levels(self.dims),
         )
@@ -271,7 +271,7 @@ def ffill(self, dim: Hashable, limit: Optional[int] = None):
         #      if needed use _maybe_groupby()
         return self._replace(
             self.unstack(dim)
-            .fillna(method="ffill", axis=1, limit=limit)
+            .ffill(axis=1, limit=limit)
             .stack()
             .reorder_levels(self.dims),
         )
diff --git a/genno/tests/compat/test_pyam.py b/genno/tests/compat/test_pyam.py
index febe3014..72cd1dd4 100644
--- a/genno/tests/compat/test_pyam.py
+++ b/genno/tests/compat/test_pyam.py
@@ -14,6 +14,11 @@
 # Skip this entire file if pyam is not installed
 pyam = pytest.importorskip("pyam", reason="pyam-iamc not installed")
 
+# Warning emitted by pandas ≥ 2.1.0 with pyam 1.9.0
+pytestmark = pytest.mark.filterwarnings(
+    "ignore:.*unique with argument that is not.*:FutureWarning:pyam.core"
+)
+
 
 @pytest.fixture(scope="session")
 def scenario():
diff --git a/genno/util.py b/genno/util.py
index 32dcb76c..23bf3ef7 100644
--- a/genno/util.py
+++ b/genno/util.py
@@ -3,6 +3,7 @@
 from inspect import Parameter, signature
 from typing import Callable, Iterable, Mapping, MutableMapping, Tuple, Type, Union
 
+import numpy as np
 import pandas as pd
 import pint
 from dask.core import literal
@@ -95,6 +96,12 @@ def parse_units(data: Iterable, registry=None) -> pint.Unit:
     """
     registry = registry or pint.get_application_registry()
 
+    # Ensure a type that is accepted by pd.unique()
+    if isinstance(data, str):
+        data = np.array([data])
+    elif not isinstance(data, (np.ndarray, pd.Index, pd.Series)):
+        data = np.array(data)
+
     unit = pd.unique(data)
 
     if len(unit) > 1: