[MXNET-867] Pooling1D with "same" padding

CONTRIBUTORS.md

@@ -180,3 +180,4 @@ List of Contributors
 * [Per Goncalves da Silva](https://github.com/perdasilva)
 * [Zhijingcheng Yu](https://github.com/jasonyu1996)
 * [Cheng-Che Lee](https://github.com/stu1130)
+* [Chaitanya Bapat](https://github.com/ChaiBapchya)

src/operator/nn/pool.h

@@ -73,7 +73,7 @@ namespace pool_enum {
 enum PoolingOpInputs {kData};
 enum PoolingOpOutputs {kOut, kMask};
 enum PoolingOpType {kMaxPooling, kAvgPooling, kSumPooling, kLpPooling};
-enum PoolingOpPadConventionType {kValid, kFull};
+enum PoolingOpPadConventionType {kValid, kFull, kSame};
 }  // namespace pool_enum
 
 /*!

src/operator/nn/pooling-inl.h

@@ -74,6 +74,7 @@ struct PoolingParam : public dmlc::Parameter<PoolingParam> {
     DMLC_DECLARE_FIELD(pooling_convention).set_default(pool_enum::kValid)
     .add_enum("full", pool_enum::kFull)
     .add_enum("valid", pool_enum::kValid)
+    .add_enum("same", pool_enum::kSame)
     .describe("Pooling convention to be applied.");
 
     DMLC_DECLARE_FIELD(stride).set_default(TShape())

src/operator/nn/pooling.cc

@@ -96,6 +96,13 @@ static bool PoolingShape(const nnvm::NodeAttrs &attrs,
     CHECK(param.p_value.has_value());
   }
   const TShape &dshape = (*in_shape)[0];
+  if (param.pooling_convention == pool_enum::kSame) {
+    CHECK_EQ(dshape.ndim(), 3U)
+      << "Pooling: Input data should be 3D in (batch, channel, x)"
+      << ". Currently 'same' supports Max Pooling 1-D";
+    CHECK(param.pad[0] == 0 && param.pad[1] == 0 && param.pad[2] == 0)
+      << "Same pooling convention disables the use of pad parameter.";
+  }
   CHECK_GE(dshape.ndim(), 3U)
       << "Pooling: Input data should be  3D in (batch, channel, x)"
       << " Or 4D in (batch, channel, y, x) "
@@ -126,11 +133,15 @@ static bool PoolingShape(const nnvm::NodeAttrs &attrs,
       oshape[2] = 1 +
                   (dshape[2] + 2 * param.pad[0] - param.kernel[0]) /
                       param.stride[0];
-    } else {
+    } else if (param.pooling_convention == pool_enum::kFull) {
       oshape[2] = 1 + static_cast<int>(std::ceil(
                           static_cast<float>(dshape[2] + 2 * param.pad[0] -
                                              param.kernel[0]) /
                           param.stride[0]));
+    } else {
+      oshape[2] = static_cast<int>(std::ceil(
+                          static_cast<float>(dshape[2] + 2 * param.pad[0]) /
+                          param.stride[0]));
     }
     out_shape->clear();
     out_shape->push_back(oshape);  // save output shape

tests/python/unittest/test_operator.py

@@ -6975,6 +6975,40 @@ def test_valid_kernel_size():
         mx.nd.array(np.random.rand(1, 1, 28, 28)),
         kernel_size=valid_kernel_size)
 
+@with_seed()
+def test_valid_max_pooling_pad_type_same():
+    import math
+    input_data = mx.nd.array(np.random.rand(1,1,10))
+    stride = 2
+    kernel = 2
+    output_data=mx.nd.Pooling(
+        input_data,
+        kernel=kernel,
+        stride=stride,
+        pad=(0,0,0),
+        pool_type='max',
+        name='pooling',
+        pooling_convention="same")
+    assert(math.ceil(input_data.shape[2]/stride) == output_data.shape[2])
+
+@with_seed()
+def test_invalid_max_pooling_pad_type_same():
+    import math
+    input_data = mx.nd.array(np.random.rand(1,1,10))
+    stride = 2
+    kernel = 2
+    pad = 2
+    assert_exception(
+        mx.nd.Pooling,
+        MXNetError,
+        input_data,
+        stride=stride,
+        kernel=kernel,
+        pad=pad,
+        pool_type='max',
+        name='pooling',
+        pooling_convention="same")
+
 if __name__ == '__main__':
     import nose
     nose.runmodule()