allow tensor in DiagonalNormal dimension (#571)

* allow tensor in DiagonalNormal dimension

Author: arrjon

bayesflow/approximators/continuous_approximator.py

@@ -535,7 +535,13 @@ def _sample(
             inference_conditions = keras.ops.broadcast_to(
                 inference_conditions, (batch_size, num_samples, *keras.ops.shape(inference_conditions)[2:])
             )
-            batch_shape = keras.ops.shape(inference_conditions)[:-1]
+
+            if hasattr(self.inference_network, "base_distribution"):
+                target_shape_len = len(self.inference_network.base_distribution.dims)
+            else:
+                # point approximator has no base_distribution
+                target_shape_len = 1
+            batch_shape = keras.ops.shape(inference_conditions)[:-target_shape_len]
         else:
             batch_shape = (num_samples,)
 

bayesflow/distributions/diagonal_normal.py

@@ -57,18 +57,18 @@ def __init__(
         self.trainable_parameters = trainable_parameters
         self.seed_generator = seed_generator or keras.random.SeedGenerator()
 
-        self.dim = None
+        self.dims = None
         self._mean = None
         self._std = None
 
     def build(self, input_shape: Shape) -> None:
         if self.built:
             return
 
-        self.dim = int(input_shape[-1])
+        self.dims = tuple(input_shape[1:])
 
-        self.mean = ops.cast(ops.broadcast_to(self.mean, (self.dim,)), "float32")
-        self.std = ops.cast(ops.broadcast_to(self.std, (self.dim,)), "float32")
+        self.mean = ops.cast(ops.broadcast_to(self.mean, self.dims), "float32")
+        self.std = ops.cast(ops.broadcast_to(self.std, self.dims), "float32")
 
         if self.trainable_parameters:
             self._mean = self.add_weight(
@@ -91,14 +91,14 @@ def log_prob(self, samples: Tensor, *, normalize: bool = True) -> Tensor:
         result = -0.5 * ops.sum((samples - self._mean) ** 2 / self._std**2, axis=-1)
 
         if normalize:
-            log_normalization_constant = -0.5 * self.dim * math.log(2.0 * math.pi) - ops.sum(ops.log(self._std))
+            log_normalization_constant = -0.5 * sum(self.dims) * math.log(2.0 * math.pi) - ops.sum(ops.log(self._std))
             result += log_normalization_constant
 
         return result
 
     @allow_batch_size
     def sample(self, batch_shape: Shape) -> Tensor:
-        return self._mean + self._std * keras.random.normal(shape=batch_shape + (self.dim,), seed=self.seed_generator)
+        return self._mean + self._std * keras.random.normal(shape=batch_shape + self.dims, seed=self.seed_generator)
 
     def get_config(self):
         base_config = super().get_config()