refactor(imports): add function to import optional packages

matplotlib is now a FloPy requirement.

Closes modflowpy#1257

flopy/export/utils.py

@@ -1511,8 +1511,10 @@ def export_array(
         a = a.copy()
         a[np.isnan(a)] = nodata
         if modelgrid.angrot != 0:
-            extra = "exporting rotated grids requires SciPy."
-            ndimage = import_optional_dependency("scipy.ndimage", extra=extra)
+            ndimage = import_optional_dependency(
+                "scipy.ndimage",
+                error_message="exporting rotated grids requires SciPy.",
+            )
 
             a = ndimage.rotate(a, modelgrid.angrot, cval=nodata)
             height_rot, width_rot = a.shape
@@ -1548,8 +1550,10 @@ def export_array(
             or modelgrid.delr[0] != modelgrid.delc[0]
         ):
             raise ValueError("GeoTIFF export require a uniform grid.")
-        extra = "GeoTIFF export requires the rasterio."
-        rasterio = import_optional_dependency("rasterio", extra=extra)
+        rasterio = import_optional_dependency(
+            "rasterio",
+            error_message="GeoTIFF export requires the rasterio.",
+        )
         dxdy = modelgrid.delc[0]
         # because this is only implemented for a structured grid,
         # we can get the xul and yul coordinate from modelgrid.xvertices(0, 0)
@@ -1709,8 +1713,9 @@ def export_contourf(
 
     """
 
-    extra = "export_contourf requires shapely."
-    shapely = import_optional_dependency("shapely", extra=extra)
+    shapely = import_optional_dependency(
+        "shapely", error_message="export_contourf requires shapely."
+    )
     from shapely import geometry
 
     from ..utils.geometry import Polygon

flopy/mf6/utils/binaryfile_utils.py

@@ -229,8 +229,10 @@ def _get_vertices(mfdict, key):
         elevations corresponding to a row column location
         """
 
-        extra = "MFOutputRequester._get_vertices() requires pandas."
-        pd = import_optional_dependency("pandas", extra=extra)
+        pd = import_optional_dependency(
+            "pandas",
+            error_message="MFOutputRequester._get_vertices() requires pandas.",
+        )
 
         mname = key[0]
         cellid = mfdict[(mname, "DISV8", "CELL2D", "cell2d_num")]

flopy/mf6/utils/mfobservation.py

@@ -209,8 +209,10 @@ def get_dataframe(
         pd.DataFrame
 
         """
-        extra = "get_dataframe() requires pandas."
-        pd = import_optional_dependency("pandas", extra=extra)
+        pd = import_optional_dependency(
+            "pandas",
+            error_message="get_dataframe() requires pandas.",
+        )
 
         data_str = self._reader(self.Obsname)
         data = self._array_to_dict(data_str)

flopy/utils/mflistfile.py

@@ -475,8 +475,10 @@ def get_dataframes(self, start_datetime="1-1-1970", diff=False):
 
         """
 
-        extra = "ListBudget.get_dataframes() requires pandas."
-        pd = import_optional_dependency("pandas", extra=extra)
+        pd = import_optional_dependency(
+            "pandas",
+            error_message="ListBudget.get_dataframes() requires pandas.",
+        )
 
         if not self._isvalid:
             return None

flopy/utils/mtlistfile.py

@@ -75,8 +75,10 @@ def parse(
             (optionally) surface-water mass budget.
             If the SFT process is not used, df_sw is None.
         """
-        extra = "MtListBudget.parse() requires pandas."
-        pd = import_optional_dependency("pandas", extra=extra)
+        pd = import_optional_dependency(
+            "pandas",
+            error_message="MtListBudget.parse() requires pandas.",
+        )
 
         self.gw_data = {}
         self.sw_data = {}
@@ -183,8 +185,10 @@ def parse(
         return df_gw, df_sw
 
     def _diff(self, df):
-        extra = "MtListBudget._diff() requires pandas."
-        pd = import_optional_dependency("pandas", extra=extra)
+        pd = import_optional_dependency(
+            "pandas",
+            error_message="MtListBudget._diff() requires pandas.",
+        )
 
         out_cols = [
             c for c in df.columns if "_out" in c and not c.startswith("net_")

flopy/utils/observationfile.py

@@ -177,8 +177,10 @@ def get_dataframe(
 
         from ..utils.utils_def import totim_to_datetime
 
-        extra = "ObsFiles.get_dataframe() requires pandas."
-        pd = import_optional_dependency("pandas", extra=extra)
+        pd = import_optional_dependency(
+            "pandas",
+            error_message="ObsFiles.get_dataframe() requires pandas.",
+        )
 
         i0 = 0
         i1 = self.data.shape[0]

flopy/utils/util_list.py

@@ -442,8 +442,10 @@ def get_dataframe(self, squeeze=False):
         Requires pandas.
 
         """
-        extra = "MfList.get_dataframe() requires pandas."
-        pd = import_optional_dependency("pandas", extra=extra)
+        pd = import_optional_dependency(
+            "pandas",
+            error_message="MfList.get_dataframe() requires pandas.",
+        )
 
         # make a dataframe of all data for all stress periods
         names = ["per", "k", "i", "j"]

flopy/utils/utl_import.py

@@ -74,7 +74,7 @@ def get_version(module: types.ModuleType) -> str:
 
 def import_optional_dependency(
     name: str,
-    extra: str = "",
+    error_message: str = "",
     errors: str = "raise",
     min_version: str | None = None,
 ):
@@ -89,7 +89,7 @@ def import_optional_dependency(
     ----------
     name : str
         The module name.
-    extra : str
+    error_message : str
         Additional text to include in the ImportError message.
     errors : str {'raise', 'warn', 'ignore'}
         What to do when a dependency is not found or its version is too old.
@@ -121,7 +121,7 @@ def import_optional_dependency(
     install_name = package_name if package_name is not None else name
 
     msg = (
-        f"Missing optional dependency '{install_name}'. {extra} "
+        f"Missing optional dependency '{install_name}'. {error_message} "
         f"Use pip or conda to install {install_name}."
     )
     try:

flopy/utils/voronoi.py

@@ -72,8 +72,10 @@ def tri2vor(tri, **kwargs):
     verts, iverts : ndarray, list of lists
 
     """
-    extra = "Voronoi requires SciPy."
-    import_optional_dependency("scipy.spatial", extra=extra)
+    import_optional_dependency(
+        "scipy.spatial",
+        error_message="Voronoi requires SciPy.",
+    )
     from scipy.spatial import Voronoi
 
     # assign local variables

flopy/utils/zonbud.py

@@ -2369,8 +2369,10 @@ def _recarray_to_dataframe(
 
     pd.DataFrame
     """
-    extra = "ZoneBudget.get_dataframes() requires pandas."
-    pd = import_optional_dependency("pandas", extra=extra)
+    pd = import_optional_dependency(
+        "pandas",
+        error_message="ZoneBudget.get_dataframes() requires pandas.",
+    )
 
     valid_index_keys = ["totim", "kstpkper"]
     s = f'index_key "{index_key}" is not valid.'
@@ -2991,8 +2993,10 @@ def _volumetric_flux(recarray, modeltime, extrapolate_kper=False):
         pd.DataFrame
 
     """
-    extra = "ZoneBudget._volumetric_flux() requires pandas."
-    pd = import_optional_dependency("pandas", extra=extra)
+    pd = import_optional_dependency(
+        "pandas",
+        error_message="ZoneBudget._volumetric_flux() requires pandas.",
+    )
 
     nper = len(modeltime.nstp)
     volumetric_data = {}