fix flax RNN interoperation, fix #663 (#665)

fix flax RNN interoperation

brainpy/_src/dnn/interoperation_flax.py

@@ -1,7 +1,7 @@
 
 import jax
 import dataclasses
-from typing import Dict
+from typing import Dict, Tuple
 from jax.tree_util import tree_flatten, tree_map, tree_unflatten
 
 from brainpy import math as bm
@@ -77,16 +77,16 @@ class ToFlaxRNNCell(RNNCellBase):
     model: DynamicalSystem
     train_params: Dict[str, jax.Array] = dataclasses.field(init=False)
 
-    def initialize_carry(self, rng, batch_dims, size=None, init_fn=None):
-      if len(batch_dims) == 0:
+    def initialize_carry(self, rng, input_shape: Tuple[int, ...]):
+      batch_dims = input_shape[:-1]
+      if len(batch_dims) == 1:
         batch_dims = 1
-      elif len(batch_dims) == 1:
-        batch_dims = batch_dims[0]
+      elif len(batch_dims) == 0:
+        batch_dims = None
       else:
-        raise NotImplementedError
-
+        raise ValueError(f'Invalid input shape: {input_shape}')
       _state_vars = self.model.vars().unique().not_subset(bm.TrainVar)
-      self.model.reset(batch_size=batch_dims)
+      self.model.reset(batch_dims)
       return [_state_vars.dict(), 0, 0.]
 
     def setup(self):
@@ -131,6 +131,9 @@ def __call__(self, carry, *inputs):
       # carray and output
       return [_state_vars.dict(), i + 1, t + share.dt], out
 
+    @property
+    def num_feature_axes(self) -> int:
+      return 1
 
 else:
   class ToFlaxRNNCell(object):

brainpy/_src/dnn/tests/test_flax.py

@@ -0,0 +1,44 @@
+# Copyright 2024 BDP Ecosystem Limited. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+
+import pytest
+
+pytest.skip('Skip this test because it is not implemented yet.',
+            allow_module_level=True)
+
+import jax
+import jax.numpy as jnp
+import flax.linen as nn
+
+import brainpy as bp
+import brainpy.math as bm
+
+bm.set_platform('cpu')
+bm.set_mode(bm.training_mode)
+
+cell = bp.dnn.ToFlaxRNNCell(bp.dyn.RNNCell(num_in=1, num_out=1, ))
+
+
+class myRNN(nn.Module):
+  @nn.compact
+  def __call__(self, x):  # x:(batch, time, features)
+    x = nn.RNN(cell)(x)  # Use nn.RNN to unfold the recurrent cell
+    return x
+
+
+def test_init():
+  model = myRNN()
+  model.init(jax.random.PRNGKey(0), jnp.ones([1, 10, 1]))  # batch,time,feature