add array_interpolate

openeo_processes_dask/process_implementations/arrays.py

@@ -33,6 +33,7 @@
     "array_find",
     "array_labels",
     "array_apply",
+    "array_interpolate_linear",
     "first",
     "last",
     "order",
@@ -234,6 +235,17 @@ def array_apply(
         )
 
 
+def array_interpolate_linear(data: ArrayLike):
+    x = np.arange(len(data))
+    valid = np.isfinite(data)
+    if len(x[valid]) < 2:
+        return data
+    data[~valid] = np.interp(
+        x[~valid], x[valid], data[valid], left=np.nan, right=np.nan
+    )
+    return data
+
+
 def first(
     data: ArrayLike,
     ignore_nodata: Optional[bool] = True,

tests/test_arrays.py

@@ -264,6 +264,21 @@ def test_array_apply(process_registry):
     assert (output_cube == [2, 3, 4, 5, 6, 7]).all()
 
 
+@pytest.mark.parametrize(
+    "data, expected",
+    [
+        ([np.nan, 1, np.nan, 6, np.nan, -8], [np.nan, 1, 3.5, 6, -1, -8]),
+        ([np.nan, 1, np.nan, np.nan], [np.nan, 1, np.nan, np.nan]),
+    ],
+)
+def test_array_interpolate_linear(data, expected):
+    assert np.array_equal(
+        array_interpolate_linear(data),
+        expected,
+        equal_nan=True,
+    )
+
+
 def test_first():
     assert first(np.array([1, 0, 3, 2])) == 1
     assert pd.isnull(first(np.array([np.nan, 2, 3]), ignore_nodata=False))