NumPy-compatible std and var

python/mxnet/ndarray/numpy/_op.py

@@ -33,7 +33,7 @@
            'rint', 'radians', 'reciprocal', 'square', 'negative', 'fix', 'ceil', 'floor',
            'trunc', 'logical_not', 'arcsinh', 'arccosh', 'arctanh', 'tensordot',
            'linspace', 'expand_dims', 'tile', 'arange', 'split', 'concatenate', 'stack', 'mean',
-           'maximum', 'minimum', 'swapaxes', 'clip', 'argmax']
+           'maximum', 'minimum', 'swapaxes', 'clip', 'argmax', 'std', 'var']
 
 
 @set_module('mxnet.ndarray.numpy')
@@ -2201,3 +2201,17 @@ def mean(a, axis=None, dtype=None, out=None, keepdims=False):  # pylint: disable
     array(0.55)
     """
     return _npi.mean(a, axis=axis, dtype=dtype, keepdims=keepdims, out=out)
+
+
+@set_module('mxnet.ndarray.numpy')
+def std(a, axis=None, dtype=None, out=None, ddof=0, keepdims=False):
+    """
+    """
+    return _npi.std(a, axis=axis, dtype=dtype, ddof=ddof, keepdims=keepdims, out=out)
+
+
+@set_module('mxnet.ndarray.numpy')
+def var(a, axis=None, dtype=None, out=None, ddof=0, keepdims=False):
+    """
+    """
+    return _npi.var(a, axis=axis, dtype=dtype, ddof=ddof, keepdims=keepdims, out=out)

python/mxnet/numpy/multiarray.py

@@ -52,7 +52,7 @@
            'degrees', 'log2', 'log1p', 'rint', 'radians', 'reciprocal', 'square', 'negative',
            'fix', 'ceil', 'floor', 'trunc', 'logical_not', 'arcsinh', 'arccosh', 'arctanh',
            'tensordot', 'linspace', 'expand_dims', 'tile', 'arange', 'split', 'concatenate',
-           'stack', 'mean', 'maximum', 'minimum', 'swapaxes', 'clip', 'argmax']
+           'stack', 'mean', 'maximum', 'minimum', 'swapaxes', 'clip', 'argmax', 'std', 'var']
 
 # Return code for dispatching indexing function call
 _NDARRAY_UNSUPPORTED_INDEXING = -1
@@ -1172,11 +1172,9 @@ def mean(self, axis=None, dtype=None, out=None, keepdims=False):  # pylint: disa
         """Returns the average of the array elements along given axis."""
         raise NotImplementedError
 
-    # TODO(junwu): Use mxnet std op instead of onp.std
     def std(self, axis=None, dtype=None, out=None, ddof=0, keepdims=False):  # pylint: disable=arguments-differ
         """Returns the standard deviation of the array elements along given axis."""
-        ret_np = self.asnumpy().std(axis=axis, dtype=dtype, out=out, ddof=ddof, keepdims=keepdims)
-        return array(ret_np, dtype=ret_np.dtype, ctx=self.context)
+        return _mx_np_op.std(self, axis=axis, dtype=dtype, ddof=ddof, keepdims=keepdims, out=out)
 
     def cumsum(self, axis=None, dtype=None, out=None):
         """Return the cumulative sum of the elements along the given axis."""
@@ -3644,3 +3642,17 @@ def mean(a, axis=None, dtype=None, out=None, keepdims=False):  # pylint: disable
     array(0.55)
     """
     return _npi.mean(a, axis=axis, dtype=dtype, keepdims=keepdims, out=out)
+
+
+@set_module('mxnet.numpy')
+def std(a, axis=None, dtype=None, out=None, ddof=0, keepdims=None):
+    """
+    """
+    return _npi.std(a, axis=axis, dtype=dtype, ddof=ddof, keepdims=keepdims, out=out)
+
+
+@set_module('mxnet.numpy')
+def var(a, axis=None, dtype=None, out=None, ddof=0, keepdims=None):
+    """
+    """
+    return _npi.var(a, axis=axis, dtype=dtype, ddof=ddof, keepdims=keepdims, out=out)

python/mxnet/symbol/numpy/_symbol.py

@@ -35,7 +35,7 @@
            'rint', 'radians', 'reciprocal', 'square', 'negative', 'fix', 'ceil', 'floor',
            'trunc', 'logical_not', 'arcsinh', 'arccosh', 'arctanh', 'tensordot',
            'linspace', 'expand_dims', 'tile', 'arange', 'split', 'concatenate', 'stack', 'mean',
-           'maximum', 'minimum', 'swapaxes', 'clip', 'argmax']
+           'maximum', 'minimum', 'swapaxes', 'clip', 'argmax', 'std', 'var']
 
 
 def _num_outputs(sym):
@@ -2569,4 +2569,18 @@ def mean(a, axis=None, dtype=None, out=None, keepdims=False):  # pylint: disable
     return _npi.mean(a, axis=axis, dtype=dtype, keepdims=keepdims, out=out)
 
 
+@set_module('mxnet.symbol.numpy')
+def std(a, axis=None, dtype=None, out=None, ddof=0, keepdims=False):
+    """
+    """
+    return _npi.std(a, axis=axis, dtype=dtype, ddof=ddof, keepdims=keepdims, out=out)
+
+
+@set_module('mxnet.symbol.numpy')
+def var(a, axis=None, dtype=None, out=None, ddof=0, keepdims=False):
+    """
+    """
+    return _npi.var(a, axis=axis, dtype=dtype, ddof=ddof, keepdims=keepdims, out=out)
+
+
 _set_np_symbol_class(_Symbol)

src/operator/numpy/np_broadcast_reduce_op.h

@@ -27,6 +27,7 @@
 
 #include <algorithm>
 #include <vector>
+#include "../nn/moments-inl.h"
 #include "../tensor/broadcast_reduce_op.h"
 
 namespace mxnet {
@@ -230,6 +231,139 @@ void NumpyReduceAxesBackwardUseInOut(const nnvm::NodeAttrs& attrs,
   ReduceAxesBackwardUseInOutImpl<xpu, OP, normalize>(ctx, small, inputs, req, outputs);
 }
 
+struct NumpyMomentsParam : public dmlc::Parameter<NumpyMomentsParam> {
+  dmlc::optional<mxnet::Tuple<int>> axis;
+  dmlc::optional<int> dtype;
+  bool keepdims;
+  int ddof;
+  DMLC_DECLARE_PARAMETER(NumpyMomentsParam) {
+    DMLC_DECLARE_FIELD(axis)
+      .set_default(dmlc::optional<mxnet::Tuple<int>>())
+      .describe("Axis or axes along which a sum is performed. The default, axis=None, will sum "
+                "all of the elements of the input array. If axis is negative it counts from the "
+                "last to the first axis.");
+    DMLC_DECLARE_FIELD(dtype)
+      .add_enum("float16", mshadow::kFloat16)
+      .add_enum("float32", mshadow::kFloat32)
+      .add_enum("float64", mshadow::kFloat64)
+      .add_enum("int8", mshadow::kInt8)
+      .add_enum("int32", mshadow::kInt32)
+      .add_enum("int64", mshadow::kInt64)
+      .set_default(dmlc::optional<int>())
+      .describe("The type of the returned array and of the accumulator in which the elements are "
+                "summed. The dtype of a is used by default unless a has an integer dtype of less "
+                "precision than the default platform integer. In that case, if a is signed then "
+                "the platform integer is used while if a is unsigned then an unsigned integer of "
+                "the same precision as the platform integer is used.");
+    DMLC_DECLARE_FIELD(ddof).set_default(0)
+      .describe("Starting value for the sum.");
+    DMLC_DECLARE_FIELD(keepdims).set_default(false)
+      .describe("If this is set to `True`, the reduced axes are left "
+                "in the result as dimension with size one.");
+  }
+};
+
+template<typename xpu, typename reducer, bool safe_acc, bool normalize = false,
+         typename OP = op::mshadow_op::identity>
+void ReduceAxesComputeWithWorkspaceImpl(const OpContext& ctx,
+                                        const std::vector<TBlob>& inputs,
+                                        const std::vector<OpReqType>& req,
+                                        const std::vector<TBlob>& outputs,
+                                        const mshadow::Tensor<xpu, 1, char>& workspace,
+                                        const mxnet::TShape& src_shape,
+                                        const mxnet::TShape& dst_shape,
+                                        const int ddof = 0) {
+  using namespace mshadow;
+  using namespace mshadow::expr;
+
+  Stream<xpu> *s = ctx.get_stream<xpu>();
+  MSHADOW_TYPE_SWITCH(inputs[0].type_flag_, DType, {
+    MSHADOW_TYPE_SWITCH(outputs[0].type_flag_, OType, {
+      const TBlob in_data = inputs[0].reshape(src_shape);
+      const TBlob out_data = outputs[0].reshape(dst_shape);
+      BROADCAST_NDIM_SWITCH(dst_shape.ndim(), NDim, {
+        broadcast::Reduce<reducer, NDim, DType, OP, safe_acc>(
+            s, out_data, req[0], workspace, in_data);
+        if (normalize) {
+          auto out = out_data.FlatTo2D<xpu, OType>(s);
+          out /= scalar<OType>(src_shape.Size()/dst_shape.Size() - ddof);
+        }
+      });
+    });
+  });
+}
+
+template<typename xpu, bool sqrt>
+void NumpyMomentsForward(const nnvm::NodeAttrs& attrs,
+                         const OpContext& ctx,
+                         const std::vector<TBlob>& inputs,
+                         const std::vector<OpReqType>& req,
+                         const std::vector<TBlob>& outputs) {
+  using namespace mshadow;
+  using namespace mshadow::expr;
+  using namespace mshadow_op;
+  using namespace mxnet_op;
+
+  CHECK_EQ(inputs.size(), 1U);
+  CHECK_EQ(req.size(), 2U);
+  CHECK_EQ(outputs.size(), 2U);
+
+  const NumpyMomentsParam& param = nnvm::get<NumpyMomentsParam>(attrs.parsed);
+
+  Stream<xpu> *s = ctx.get_stream<xpu>();
+
+  const TBlob& data = inputs[0];
+  const TBlob& moment = outputs[0];
+  const TBlob& mean = outputs[1];
+
+  mxnet::TShape small;
+  if (param.keepdims) {
+    small = moment.shape_;
+  } else {
+    small = NumpyReduceAxesShapeImpl(data.shape_, param.axis, true);
+  }
+
+  mxnet::TShape src_shape, dst_shape;
+  BroadcastReduceShapeCompact(data.shape_, small, &src_shape, &dst_shape);
+
+  MSHADOW_TYPE_SWITCH(inputs[0].type_flag_, DType, {
+    MSHADOW_TYPE_SWITCH(outputs[0].type_flag_, OType, {
+      // Get workspace and temp space for data - mean
+      size_t workspace_size = 0;
+      BROADCAST_NDIM_SWITCH(dst_shape.ndim(), NDim, {
+        workspace_size = broadcast::ReduceWorkspaceSize<NDim, DType>(
+          s, dst_shape, req[0], src_shape);;
+      });
+      size_t temp_data_size = data.shape_.Size() * sizeof(DType);
+      size_t temp_mem_size = temp_data_size + workspace_size;
+      Tensor<xpu, 1, char> temp_mem =
+        ctx.requested[0].get_space_typed<xpu, 1, char>(Shape1(temp_mem_size), s);
+      DType *temp_data_ptr = reinterpret_cast<DType*>(temp_mem.dptr_);
+      char *workspace_ptr = temp_mem.dptr_ + temp_data_size;
+      Tensor<xpu, 1, char> workspace(workspace_ptr, Shape1(workspace_size), s);
+      // Compute mean
+      ReduceAxesComputeWithWorkspaceImpl<xpu, mshadow_op::sum, true, true>(
+        ctx, inputs, {kWriteTo}, {mean}, workspace, src_shape, dst_shape);
+      // Compute data - mean
+      Shape<6> data_shape, mean_shape;
+      for (int i = 0; i < 6; ++i) {
+        data_shape[i] = (i < data.shape_.ndim()) ? data.shape_[i] : 1;
+        mean_shape[i] = (i < small.ndim()) ? small[i] : 1;
+      }
+      Kernel<VarBroadcastKernel, xpu>::Launch(s, data_shape.Size(), temp_data_ptr,
+        data.dptr<DType>(), mean.dptr<DType>(), data_shape, mean_shape);
+      Tensor<xpu, 1, DType> temp_data_tensor(temp_data_ptr, Shape1(data.shape_.Size()), s);
+      TBlob temp_data_blob = TBlob(temp_data_tensor).reshape(data.shape_);
+      ReduceAxesComputeWithWorkspaceImpl<xpu, mshadow_op::sum, true, true>(
+        ctx, {temp_data_blob}, {req[0]}, {moment}, workspace, src_shape, dst_shape, param.ddof);
+      if (sqrt) {
+        Tensor<xpu, 1, OType> moment_tensor = moment.FlatTo1D<xpu, OType>(s);
+        moment_tensor = F<mshadow_op::square_root>(moment_tensor);
+      }
+    });
+  });
+}
+
 template<typename xpu>
 void NumpyBroadcastToForward(const nnvm::NodeAttrs& attrs,
                              const OpContext& ctx,

src/operator/numpy/np_broadcast_reduce_op_value.cc

@@ -29,6 +29,7 @@ namespace mxnet {
 namespace op {
 
 DMLC_REGISTER_PARAMETER(NumpyReduceAxesParam);
+DMLC_REGISTER_PARAMETER(NumpyMomentsParam);
 
 inline bool NumpySumType(const nnvm::NodeAttrs& attrs,
                          std::vector<int> *in_attrs,
@@ -153,6 +154,94 @@ NNVM_REGISTER_OP(_backward_np_mean)
 .set_num_inputs(1)
 .set_attr<FCompute>("FCompute<cpu>", NumpyReduceAxesBackwardUseNone<cpu, true>);
 
+inline bool NumpyMomentsShape(const nnvm::NodeAttrs& attrs,
+                              std::vector<TShape> *in_attrs,
+                              std::vector<TShape> *out_attrs) {
+  CHECK_EQ(in_attrs->size(), 1U);
+  CHECK_EQ(out_attrs->size(), 2U);
+  if (!shape_is_known(in_attrs->at(0))) {
+    return false;
+  }
+  const NumpyMomentsParam& param = nnvm::get<NumpyMomentsParam>(attrs.parsed);
+  mxnet::TShape out_shape = NumpyReduceAxesShapeImpl((*in_attrs)[0], param.axis, param.keepdims);
+  SHAPE_ASSIGN_CHECK(*out_attrs, 0, out_shape);
+  SHAPE_ASSIGN_CHECK(*out_attrs, 1, out_shape);
+
+  return shape_is_known(out_attrs->at(0)) && shape_is_known(out_attrs->at(1));
+}
+
+inline bool NumpyMomentsType(const nnvm::NodeAttrs& attrs,
+                             std::vector<int> *in_attrs,
+                             std::vector<int> *out_attrs) {
+  CHECK_EQ(in_attrs->size(), 1U);
+  CHECK_EQ(out_attrs->size(), 2U);
+  const NumpyMomentsParam &param = nnvm::get<NumpyMomentsParam>(attrs.parsed);
+
+  if (param.dtype.has_value()) {
+    TYPE_ASSIGN_CHECK(*out_attrs, 0, param.dtype.value());
+  } else {
+    TYPE_ASSIGN_CHECK(*out_attrs, 0, in_attrs->at(0));
+    TYPE_ASSIGN_CHECK(*in_attrs, 0, out_attrs->at(0));
+  }
+  TYPE_ASSIGN_CHECK(*out_attrs, 1, in_attrs->at(0));
+
+  return out_attrs->at(0) != -1 && in_attrs->at(0) != -1;
+}
+
+NNVM_REGISTER_OP(_npi_std)
+.set_num_inputs(1)
+.set_num_outputs(2)
+.set_attr_parser(ParamParser<NumpyMomentsParam>)
+.set_attr<mxnet::FInferShape>("FInferShape", NumpyMomentsShape)
+.set_attr<nnvm::FInferType>("FInferType", NumpyMomentsType)
+.set_attr<nnvm::FListInputNames>("FListInputNames",
+  [](const NodeAttrs& attrs) {
+    return std::vector<std::string>{"a"};
+  })
+.set_attr<nnvm::FListOutputNames>("FListOutputNames",
+  [](const NodeAttrs& attrs) {
+    return std::vector<std::string>{"std", "mean"};
+  })
+.set_attr<nnvm::FNumVisibleOutputs>("FNumVisibleOutputs",
+  [](const NodeAttrs& attrs) {
+    return 1;
+  })
+.add_argument("a", "NDArray-or-Symbol", "The input")
+.add_arguments(NumpyMomentsParam::__FIELDS__())
+.set_attr<FCompute>("FCompute<cpu>", NumpyMomentsForward<cpu, true>)
+.set_attr<FResourceRequest>("FResourceRequest",
+  [](const NodeAttrs& attrs) {
+    return std::vector<ResourceRequest>{ResourceRequest::kTempSpace};
+  })
+.set_attr<nnvm::FGradient>("FGradient", MakeZeroGradNodes);
+
+NNVM_REGISTER_OP(_npi_var)
+.set_num_inputs(1)
+.set_num_outputs(2)
+.set_attr_parser(ParamParser<NumpyMomentsParam>)
+.set_attr<mxnet::FInferShape>("FInferShape", NumpyMomentsShape)
+.set_attr<nnvm::FInferType>("FInferType", NumpyMomentsType)
+.set_attr<nnvm::FListInputNames>("FListInputNames",
+  [](const NodeAttrs& attrs) {
+    return std::vector<std::string>{"a"};
+  })
+.set_attr<nnvm::FListOutputNames>("FListOutputNames",
+  [](const NodeAttrs& attrs) {
+    return std::vector<std::string>{"var", "mean"};
+  })
+.set_attr<nnvm::FNumVisibleOutputs>("FNumVisibleOutputs",
+  [](const NodeAttrs& attrs) {
+    return 1;
+  })
+.add_argument("a", "NDArray-or-Symbol", "The input")
+.add_arguments(NumpyMomentsParam::__FIELDS__())
+.set_attr<FCompute>("FCompute<cpu>", NumpyMomentsForward<cpu, false>)
+.set_attr<FResourceRequest>("FResourceRequest",
+  [](const NodeAttrs& attrs) {
+    return std::vector<ResourceRequest>{ResourceRequest::kTempSpace};
+  })
+.set_attr<nnvm::FGradient>("FGradient", MakeZeroGradNodes);
+
 bool NumpyBroadcastToShape(const nnvm::NodeAttrs& attrs,
                            mxnet::ShapeVector *in_attrs,
                            mxnet::ShapeVector *out_attrs) {

src/operator/numpy/np_broadcast_reduce_op_value.cu

@@ -44,6 +44,12 @@ NNVM_REGISTER_OP(_npi_mean)
 NNVM_REGISTER_OP(_backward_np_mean)
 .set_attr<FCompute>("FCompute<gpu>", NumpyReduceAxesBackwardUseNone<gpu, true>);
 
+NNVM_REGISTER_OP(_npi_std)
+.set_attr<FCompute>("FCompute<gpu>", NumpyMomentsForward<gpu, true>);
+
+NNVM_REGISTER_OP(_npi_var)
+.set_attr<FCompute>("FCompute<gpu>", NumpyMomentsForward<gpu, false>);
+
 NNVM_REGISTER_OP(_np_broadcast_to)
 .set_attr<FCompute>("FCompute<gpu>", NumpyBroadcastToForward<gpu>);