src/operator/numpy/np_constraint_check.cc

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

/*!
 * \file np_constraint_check.cc
 * \brief helper function for constraint check
 */

#include "./np_constraint_check.h"

namespace mxnet {
namespace op {

template <>
void GetReduceOutput<cpu>(mshadow::Stream<cpu>* s, const TBlob& output_blob, bool* red_output) {
  *red_output = static_cast<bool>(*output_blob.dptr<bool>());
}

inline bool ConstraintCheckShape(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(), 1U);
  if (!shape_is_known(in_attrs->at(0))) {
    return false;
  }
  SHAPE_ASSIGN_CHECK(*out_attrs, 0, TShape(0, -1))
  return true;
}

inline bool ConstraintCheckType(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(), 1U);
  CHECK(in_attrs->at(0) == mshadow::kBool);
  TYPE_ASSIGN_CHECK(*out_attrs, 0, mshadow::kBool);
  return out_attrs->at(0) != -1 && in_attrs->at(0) != -1;
}

DMLC_REGISTER_PARAMETER(ConstraintCheckParam);

NNVM_REGISTER_OP(_npx_constraint_check)
    .describe(R"code(This operator will check if all the elements in a boolean tensor is true.
If not, ValueError exception will be raised in the backend with given error message.
In order to evaluate this operator, one should multiply the origin tensor by the return value
of this operator to force this operator become part of the computation graph, otherwise the check
would not be working under symoblic mode.

Example:

loc = np.zeros((2,2))
scale = np.array(#some_value)
constraint = (scale > 0)
np.random.normal(loc, scale * npx.constraint_check(constraint, 'Scale should be larger than zero'))

If elements in the scale tensor are all bigger than zero, npx.constraint_check would return
`np.array(True)`, which will not change the value of `scale` when multiplied by.
If some of the elements in the scale tensor violate the constraint, i.e. there exists `False` in
the boolean tensor `constraint`, a `ValueError` exception with given message
'Scale should be larger than zero' would be raised.

)code" ADD_FILELINE)
    .set_attr_parser(ParamParser<ConstraintCheckParam>)
    .set_num_inputs(1)
    .set_num_outputs(1)
    .set_attr<nnvm::FListInputNames>("FListInputNames",
                                     [](const NodeAttrs& attrs) {
                                       return std::vector<std::string>{"input"};
                                     })
    .set_attr<mxnet::FInferShape>("FInferShape", ConstraintCheckShape)
    .set_attr<nnvm::FInferType>("FInferType", ConstraintCheckType)
    .set_attr<FResourceRequest>("FResourceRequest",
                                [](const NodeAttrs& attrs) {
                                  return std::vector<ResourceRequest>{ResourceRequest::kTempSpace};
                                })
    .set_attr<FCompute>("FCompute<cpu>", ConstraintCheckForward<cpu>)
    .set_attr<nnvm::FGradient>("FGradient", MakeZeroGradNodes)
    .add_argument("input", "NDArray-or-Symbol", "Input boolean array")
    .add_arguments(ConstraintCheckParam::__FIELDS__());

}  // namespace op
}  // namespace mxnet