docs: add type hints for array layout module

qpretrieve/data_array_layout.py

@@ -16,8 +16,18 @@ def get_allowed_array_layouts() -> list:
     ]
 
 
-def convert_data_to_3d_array_layout(data):
-    """Convert the data to the 3d array_layout."""
+def convert_data_to_3d_array_layout(
+        data: np.ndarray) -> tuple[np.ndarray, str]:
+    """Convert the data to the 3d array_layout
+
+    Returns
+    -------
+    data
+        3d version of the data
+    array_layout
+        original array layout for future reference
+
+    """
     if len(data.shape) == 3:
         if data.shape[-1] in [1, 2, 3]:
             # take the first slice (we have alpha or RGB information)
@@ -41,9 +51,15 @@ def convert_data_to_3d_array_layout(data):
     return data.copy(), array_layout
 
 
-def convert_3d_data_to_array_layout(data, array_layout):
+def convert_3d_data_to_array_layout(
+        data: np.ndarray, array_layout: str) -> np.ndarray:
     """Convert the 3d data to the desired `array_layout`.
 
+    Returns
+    -------
+    data_out
+        input `data` with the given `array layout`
+
     Notes
     -----
     Currently, this function is limited to converting from 3d to other
@@ -68,7 +84,7 @@ def convert_3d_data_to_array_layout(data, array_layout):
     return data
 
 
-def _convert_rgb_to_3d(data_input):
+def _convert_rgb_to_3d(data_input: np.ndarray) -> tuple[np.ndarray, str]:
     data = data_input[:, :, 0]
     data = data[np.newaxis, :, :]
     array_layout = "rgb"
@@ -77,29 +93,29 @@ def _convert_rgb_to_3d(data_input):
     return data, array_layout
 
 
-def _convert_rgba_to_3d(data_input):
+def _convert_rgba_to_3d(data_input: np.ndarray) -> tuple[np.ndarray, str]:
     data, _ = _convert_rgb_to_3d(data_input)
     array_layout = "rgba"
     return data, array_layout
 
 
-def _convert_2d_to_3d(data_input):
+def _convert_2d_to_3d(data_input: np.ndarray) -> tuple[np.ndarray, str]:
     data = data_input[np.newaxis, :, :]
     array_layout = "2d"
     return data, array_layout
 
 
-def _convert_3d_to_rgb(data_input):
+def _convert_3d_to_rgb(data_input: np.ndarray) -> np.ndarray:
     data = data_input[0]
     data = np.dstack((data, data, data))
     return data
 
 
-def _convert_3d_to_rgba(data_input):
+def _convert_3d_to_rgba(data_input: np.ndarray) -> np.ndarray:
     data = data_input[0]
     data = np.dstack((data, data, data, np.ones_like(data)))
     return data
 
 
-def _convert_3d_to_2d(data_input):
+def _convert_3d_to_2d(data_input: np.ndarray) -> np.ndarray:
     return data_input[0]