make matplotlib optional

README.md

@@ -50,6 +50,7 @@ $ pip install git+https://github.com/pysal/esda@main
 
 - `numba>=0.57` - used to accelerate computational geometry and permutation-based statistical inference.
 - `rtree>=1.0` - required for `esda.topo.isolation()`
+- `matplotlib` - required for `esda.moran.explore()`
 
 ## Contribute
 

esda/moran.py

@@ -16,7 +16,6 @@
 import scipy.stats as stats
 from libpysal.weights import W
 from libpysal.weights.spatial_lag import lag_spatial
-from matplotlib import colors
 from scipy import sparse
 
 from .crand import _prepare_univariate
@@ -1786,6 +1785,11 @@ def _explore_local_moran(moran_local, gdf, crit_value, **kwargs):
         folium.Map
     """
 
+    try:
+        from matplotlib import colors
+    except ImportError:
+        raise ImportError("matplotlib library must be installed to use the explore feature") from None
+
     gdf = gdf.copy()
     gdf["Moran Cluster"] = moran_local.get_cluster_labels(crit_value)
     gdf["p-value"] = moran_local.p_sim