allow for activation in finetuning head to be customizable, addressing …

…#23

enformer_pytorch/finetune.py

@@ -1,4 +1,6 @@
 import torch
+from typing import Optional
+
 from copy import deepcopy
 from contextlib import contextmanager
 import torch.nn.functional as F
@@ -13,6 +15,9 @@
 def exists(val):
     return val is not None
 
+def default(val, d):
+    return val if exists(val) else d
+
 @contextmanager
 def null_context():
     yield
@@ -101,6 +106,7 @@ def __init__(
         bottleneck_num_codebooks = 4,
         bottleneck_decay = 0.9,
         transformer_embed_fn: nn.Module = nn.Identity(),
+        output_activation: Optional[nn.Module] = nn.Softplus(),
         auto_set_target_length = True
     ):
         super().__init__()
@@ -135,9 +141,9 @@ def __init__(
             nn.LayerNorm(enformer_hidden_dim) if post_transformer_embed else None
         )
 
-        self.to_tracks = nn.Sequential(
+        self.to_tracks = Sequential(
             nn.Linear(enformer_hidden_dim, num_tracks),
-            nn.Softplus()
+            output_activation
         )
 
     def forward(
@@ -179,7 +185,8 @@ def __init__(
         bottleneck_num_memories = 256,
         bottleneck_num_codebooks = 4,
         bottleneck_decay = 0.9,
-        auto_set_target_length = True
+        auto_set_target_length = True,
+        output_activation: Optional[nn.Module] = nn.Softplus()
     ):
         super().__init__()
         assert isinstance(enformer, Enformer)
@@ -204,6 +211,8 @@ def __init__(
         self.to_context_weights = nn.Parameter(torch.randn(context_dim, enformer_hidden_dim))
         self.to_context_bias = nn.Parameter(torch.randn(context_dim))
 
+        self.activation = default(output_activation, nn.Identity())
+
     def forward(
         self,
         seq,
@@ -229,7 +238,7 @@ def forward(
 
         pred = einsum('b n d, t d -> b n t', embeddings, weights) + bias
 
-        pred = F.softplus(pred)
+        pred = self.activation(pred)
 
         if not exists(target):
             return pred
@@ -250,7 +259,8 @@ def __init__(
         bottleneck_num_memories = 256,
         bottleneck_num_codebooks = 4,
         bottleneck_decay = 0.9,
-        auto_set_target_length = True
+        auto_set_target_length = True,
+        output_activation: Optional[nn.Module] = None
     ):
         super().__init__()
         assert isinstance(enformer, Enformer)
@@ -286,10 +296,10 @@ def __init__(
         self.to_key_values = nn.Linear(context_dim, inner_dim * 2, bias = False)
         self.to_out = nn.Linear(inner_dim, enformer_hidden_dim)
 
-        self.to_pred  = nn.Sequential(
+        self.to_pred  = Sequential(
             nn.Linear(enformer_hidden_dim, 1),
             Rearrange('b c ... 1 -> b ... c'),
-            nn.Softplus()
+            output_activation
         )
 
     def forward(

setup.py

@@ -4,7 +4,7 @@
   name = 'enformer-pytorch',
   packages = find_packages(exclude=[]),
   include_package_data = True,
-  version = '0.6.4',
+  version = '0.7.0',
   license='MIT',
   description = 'Enformer - Pytorch',
   author = 'Phil Wang',