xidulu commented on a change in pull request #16638: [Numpy] Add sampling 
method for bernoulli
URL: https://github.com/apache/incubator-mxnet/pull/16638#discussion_r344610882
 
 

 ##########
 File path: src/operator/numpy/random/np_bernoulli_op.h
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+/*
+ * 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.
+ */
+
+/*!
+ * Copyright (c) 2019 by Contributors
+ * \file np_bernoulli_op.h
+ * \brief Operator for numpy sampling from bernoulli distribution.
+ */
+#ifndef MXNET_OPERATOR_NUMPY_RANDOM_NP_BERNOULLI_OP_H_
+#define MXNET_OPERATOR_NUMPY_RANDOM_NP_BERNOULLI_OP_H_
+
+#include <mxnet/operator_util.h>
+#include <algorithm>
+#include <string>
+#include <vector>
+#include "../../elemwise_op_common.h"
+#include "../../mshadow_op.h"
+#include "../../mxnet_op.h"
+#include "../../operator_common.h"
+#include "../../tensor/elemwise_binary_broadcast_op.h"
+#include "./dist_common.h"
+
+namespace mxnet {
+namespace op {
+
+struct NumpyBernoulliParam : public dmlc::Parameter<NumpyBernoulliParam> {
+  dmlc::optional<float> prob;
+  dmlc::optional<float> logit;
+  std::string ctx;
+  int dtype;
+  bool is_logit;
+  dmlc::optional<mxnet::Tuple<int>> size;
+  DMLC_DECLARE_PARAMETER(NumpyBernoulliParam) {
+    DMLC_DECLARE_FIELD(prob);
+    DMLC_DECLARE_FIELD(logit);
+    DMLC_DECLARE_FIELD(size)
+        .set_default(dmlc::optional<mxnet::Tuple<int>>())
+        .describe(
+            "Output shape. If the given shape is, "
+            "e.g., (m, n, k), then m * n * k samples are drawn. "
+            "Default is None, in which case a single value is returned.");
+    DMLC_DECLARE_FIELD(ctx).set_default("cpu").describe(
+        "Context of output, in format [cpu|gpu|cpu_pinned](n)."
+        " Only used for imperative calls.");
+    DMLC_DECLARE_FIELD(dtype)
+        .add_enum("uint8", mshadow::kUint8)
+        .add_enum("int32", mshadow::kInt32)
+        .add_enum("float32", mshadow::kFloat32)
+        .add_enum("float64", mshadow::kFloat64)
+        .add_enum("float16", mshadow::kFloat16)
+        .add_enum("bool", mshadow::kBool)
+        .set_default(mshadow::kFloat32)
+        .describe(
+            "DType of the output in case this can't be inferred. "
+            "Defaults to float32 if not defined (dtype=None).");
+    DMLC_DECLARE_FIELD(is_logit);
+  }
+};
+
+inline bool NumpyBernoulliOpType(const nnvm::NodeAttrs &attrs,
+                               std::vector<int> *in_attrs,
+                               std::vector<int> *out_attrs) {
+  const NumpyBernoulliParam &param = 
nnvm::get<NumpyBernoulliParam>(attrs.parsed);
+  int otype = param.dtype;
+  (*out_attrs)[0] = otype;
+  return true;
+}
+
+namespace mxnet_op {
+
+struct prob_to_logit {
+  MSHADOW_XINLINE static void Map(index_t i, float* uniforms) {
+    float prob = uniforms[i];
+    uniforms[i] = log(prob) - log(1 - prob);
+  }
+};
+
+template <int ndim, typename IType, typename OType>
+struct bernoulli_kernel {
+  MSHADOW_XINLINE static void Map(index_t i,
+                                  const Shape<ndim> &stride,
+                                  const Shape<ndim> &oshape,
+                                  IType *inputs, float* threshold, OType *out) 
{
+    Shape<ndim> coord = unravel(i, oshape);
+    auto idx = static_cast<index_t>(dot(coord, stride));
+    out[i] =  inputs[idx] > threshold[i] ? OType(1) : OType(0);
+  }
+};
+
+template <typename OType>
+struct scalar_bernoulli_kernel {
+  MSHADOW_XINLINE static void Map(index_t i, float inputs, float *threshold,
+                                  OType *out) {
+    out[i] = inputs > threshold[i] ? OType(1) : OType(0);
+  }
+};
+
+template <typename IType>
+struct check_legal_prob_kernel {
+  MSHADOW_XINLINE static void Map(index_t i, IType *scalar, float* flag) {
+    if (scalar[i] < 0.0 || scalar[i] > 1.0) {
+      flag[0] = -1.0;
+    }
+  }
+};
+
+}  // namespace mxnet_op
+
+template <typename xpu>
+void NumpyBernoulliForward(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 mxnet_op;
+  const NumpyBernoulliParam &param = 
nnvm::get<NumpyBernoulliParam>(attrs.parsed);
+  Stream<xpu> *s = ctx.get_stream<xpu>();
+  index_t output_len = outputs[0].Size();
+  Random<xpu, float> *prnd = ctx.requested[0].get_random<xpu, float>(s);
+  Tensor<xpu, 1, float> workspace =
+      ctx.requested[1].get_space_typed<xpu, 1, float>(Shape1(output_len + 1), 
s);
+  Tensor<xpu, 1, float> uniform_tensor = workspace.Slice(0, output_len);
+  Tensor<xpu, 1, float> indicator_device = workspace.Slice(output_len, 
output_len + 1);
+  float indicator_host = 1.0;
+  float *indicator_device_ptr = indicator_device.dptr_;
+  Kernel<set_zero, xpu>::Launch(s, 1, indicator_device_ptr);
+  prnd->SampleUniform(&uniform_tensor, 0.0, 1.0);
+  if (param.prob.has_value()) {
+    // scalar prob input
+    CHECK_LE(param.prob.value(), 1.0) << "ValueError: expect probs >= 0 && 
probs <= 1";
+    CHECK_GE(param.prob.value(), 0.0) << "ValueError: expect probs >= 0 && 
probs <= 1";
+    MSHADOW_TYPE_SWITCH_WITH_BOOL(outputs[0].type_flag_, OType, {
+      Kernel<scalar_bernoulli_kernel<OType>, xpu>::Launch(
+        s, outputs[0].Size(), param.prob.value(),
+        uniform_tensor.dptr_, outputs[0].dptr<OType>());
+    });
+  } else if (param.logit.has_value()) {
+    // scalar logit input
+    // sigmoid(x) > u  <=> x > logit(u)
+    Kernel<prob_to_logit, xpu>::Launch(s, outputs[0].Size(),
+                                         uniform_tensor.dptr_);
+    MSHADOW_TYPE_SWITCH_WITH_BOOL(outputs[0].type_flag_, OType, {
+      Kernel<scalar_bernoulli_kernel<OType>, xpu>::Launch(
+        s, outputs[0].Size(), param.logit.value(),
+        uniform_tensor.dptr_, outputs[0].dptr<OType>());
+    });
+  } else {
+    if (param.is_logit) {
+      // tensor logit input
+      Kernel<prob_to_logit, xpu>::Launch(s, outputs[0].Size(),
+                                         uniform_tensor.dptr_);
+    } else {
+      // tensor prob input
+      // sigmoid(x) > u  <=> x > logit(u)
+      MSHADOW_TYPE_SWITCH(inputs[0].type_flag_, IType, {
+        Kernel<check_legal_prob_kernel<IType>, xpu>::Launch(
+            s, inputs[0].Size(), inputs[0].dptr<IType>(), 
indicator_device_ptr);
+      });
+      _copy<xpu>(&indicator_host, indicator_device_ptr);
+      CHECK_GE(indicator_host, 0.0)
+          << "ValueError: expect probs >= 0 && probs <= 1";
+    }
+    mxnet::TShape new_lshape, new_oshape;
+    int ndim = FillShape(inputs[0].shape_, inputs[0].shape_, outputs[0].shape_,
+                         &new_lshape, &new_lshape, &new_oshape);
+    MSHADOW_TYPE_SWITCH(inputs[0].type_flag_, IType, {
+       MSHADOW_TYPE_SWITCH_WITH_BOOL(outputs[0].type_flag_, OType, {
 
 Review comment:
   Thx for pointing out, working on it

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