avoid imports from optional packages

Author: ATL2001

src/spatial_polars/_utils.py

@@ -4,9 +4,8 @@
 
 import numpy as np
 import polars as pl
-from palettable.palette import Palette
 from polars import selectors as cs
-from matplotlib.colors import Colormap
+
 
 
 def validate_col_exists_in_df(df: pl.DataFrame, col: Any):
@@ -49,6 +48,8 @@ def validate_cmap_input(
         )
 
     if cmap_type == "continuous":
+        from palettable.palette import Palette
+        from matplotlib.colors import Colormap
         if isinstance(cmap, (Palette, Colormap)) is False:
             # verify continuous cmaps get a cmap or appropriate type.
             raise ValueError(

src/spatial_polars/spatialframe.py

@@ -8,19 +8,19 @@
 import shapely
 import geoarrow.pyarrow as ga
 from geoarrow.pyarrow import io as gaio
-from lonboard import viz, PathLayer, PolygonLayer, ScatterplotLayer
-from lonboard.colormap import apply_continuous_cmap, apply_categorical_cmap
+
 from polars import col as c
 
 from ._utils import validate_cmap_input, validate_width_and_radius_input
 
 if TYPE_CHECKING:
+    from lonboard import Map, PathLayer, PolygonLayer, ScatterplotLayer
     from lonboard.types.layer import (
         PathLayerKwargs,
         PolygonLayerKwargs,
         ScatterplotLayerKwargs,
     )
-    from lonboard.types.map import Map, MapKwargs
+    from lonboard.types.map import MapKwargs
     from io import BytesIO
     from numpy.typing import NDArray
     from palettable.palette import Palette
@@ -650,6 +650,7 @@ def viz(
         >>> df.spatial.viz()
 
         """
+        from lonboard import viz
         geoarrow_table = self.to_geoarrow(geometry_name)
 
         return viz(
@@ -808,6 +809,9 @@ def to_scatterplotlayer(
 
 
         """
+        from lonboard import ScatterplotLayer
+        from lonboard.colormap import apply_continuous_cmap, apply_categorical_cmap
+
         validate_cmap_input(
             self._df,
             fill_cmap_col,
@@ -1022,6 +1026,10 @@ def to_pathlayer(
 
 
         """
+        from lonboard import PathLayer
+        from lonboard.colormap import apply_continuous_cmap, apply_categorical_cmap
+
+
         validate_cmap_input(
             self._df, cmap_col, cmap_type, cmap, alpha, normalize_cmap_col
         )
@@ -1217,6 +1225,9 @@ def to_polygonlayer(
         Implementation varies slightly from Lonboard for the setting of color and width to make it easy to use from the SpatialFrame.
 
         """
+        from lonboard import PolygonLayer
+        from lonboard.colormap import apply_continuous_cmap, apply_categorical_cmap
+
         validate_cmap_input(
             self._df,
             fill_cmap_col,