Allow Y to be a tensor (#180)

* Allow Y to be a tensor

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Update pgbart.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: aloctavodia

pymc_bart/pgbart.py

@@ -138,6 +138,11 @@ def __init__(  # noqa: PLR0915
         else:
             self.X = self.bart.X
 
+        if isinstance(self.bart.Y, Variable):
+            self.Y = self.bart.Y.eval()
+        else:
+            self.Y = self.bart.Y
+
         self.missing_data = np.any(np.isnan(self.X))
         self.m = self.bart.m
         self.response = self.bart.response
@@ -166,26 +171,26 @@ def __init__(  # noqa: PLR0915
             if rule is ContinuousSplitRule:
                 self.X[:, idx] = jitter_duplicated(self.X[:, idx], np.nanstd(self.X[:, idx]))
 
-        init_mean = self.bart.Y.mean()
+        init_mean = self.Y.mean()
         self.num_observations = self.X.shape[0]
         self.num_variates = self.X.shape[1]
         self.available_predictors = list(range(self.num_variates))
 
         # if data is binary
         self.leaf_sd = np.ones((self.trees_shape, self.leaves_shape))
 
-        y_unique = np.unique(self.bart.Y)
+        y_unique = np.unique(self.Y)
         if y_unique.size == 2 and np.all(y_unique == [0, 1]):
             self.leaf_sd *= 3 / self.m**0.5
         else:
-            self.leaf_sd *= self.bart.Y.std() / self.m**0.5
+            self.leaf_sd *= self.Y.std() / self.m**0.5
 
         self.running_sd = [
             RunningSd((self.leaves_shape, self.num_observations)) for _ in range(self.trees_shape)
         ]
 
         self.sum_trees = np.full(
-            (self.trees_shape, self.leaves_shape, self.bart.Y.shape[0]), init_mean
+            (self.trees_shape, self.leaves_shape, self.Y.shape[0]), init_mean
         ).astype(config.floatX)
         self.sum_trees_noi = self.sum_trees - init_mean
         self.a_tree = Tree.new_tree(