Simplify dependencies. Make statsmodels optional.

pyproject.toml

@@ -52,16 +52,13 @@ classifiers = [
     "Topic :: Utilities",
 ]
 dependencies = [
-    "numpy>=1.22.4, <=2.0.1",  # >= 1.22 for quantile method support in xarray. https://github.com/statsmodels/statsmodels/issues/9333
-    "dask",
+    "numpy",
+    "xarray[accel]",
+    "dask[distributed]",
     "pandas",
-    "xarray[parallel]",     # numbagg (llvmlite) is a pain to install with pip
-    "bottleneck",           # speeds up Xarray
-    "flox",                 # speeds up Xarray
     "pyyaml>=6.0.1",
     "xmltodict",
     "scipy",
-    "statsmodels",
     "matplotlib",
     "netCDF4>=1.6.4",
     "nc-time-axis>=1.4.1"  # plot dependency of xarray

src/dtscalibration/calibrate_utils.py

@@ -1,6 +1,5 @@
 import numpy as np
 import scipy.sparse as sp
-import statsmodels.api as sm
 import xarray as xr
 from scipy.sparse import linalg as ln
 
@@ -2124,6 +2123,15 @@ def wls_stats(X, y, w=1.0, calc_cov=False, x0=None, return_werr=False, verbose=F
     p_cov : ndarray
         The covariance of the solution.
     """
+    try:
+        import statsmodels.api as sm
+    except ImportError as err:
+        msg = (
+            "Statsmodels has to be installed for this function.\n"
+            "Install it with `pip install statsmodels`."
+        )
+        raise ImportError(msg) from err
+
     y = np.asarray(y)
     w = np.asarray(w)
 

src/dtscalibration/variance_helpers.py

@@ -76,7 +76,14 @@ def variance_stokes_exponential_helper(
 
     if use_statsmodels:
         # returns the same answer with statsmodel
-        import statsmodels.api as sm
+        try:
+            import statsmodels.api as sm
+        except ImportError as err:
+            msg = (
+                "Statsmodels has to be installed for this function.\n"
+                "Install it with `pip install statsmodels`."
+            )
+            raise ImportError(msg) from err
 
         X = sp.coo_matrix(
             (data, coords), shape=(nt * n_locs, ddof), dtype=float, copy=False