Added LayerNorm implementation.

Author: Dusan Malic

torchsparse/nn/modules/__init__.py

@@ -3,3 +3,4 @@
 from .conv import *
 from .pooling import *
 from .detection import *
+from .layernorm import *

torchsparse/nn/modules/layernorm.py

@@ -0,0 +1,23 @@
+from torch import nn
+
+from torchsparse.sparse_tensor import *
+
+__all__ = ['LayerNorm']
+
+
+class LayerNorm(nn.LayerNorm):
+    def __init__(self,
+                 normalized_shape,
+                 eps=1e-05,
+                 elementwise_affine=True):
+        super().__init__(normalized_shape, eps=eps, elementwise_affine=elementwise_affine)
+
+    def forward(self, inputs):
+        features = inputs.F
+        coords = inputs.C
+        cur_stride = inputs.s
+        output_features = super().forward(features)
+        output_tensor = SparseTensor(output_features, coords, cur_stride)
+        output_tensor.coord_maps = inputs.coord_maps
+        output_tensor.kernel_maps = inputs.kernel_maps
+        return output_tensor