Merge pull request #5300 from kuke/ctc_edit_distance_dev

Add edit distance operator

paddle/operators/edit_distance_op.cc

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+Licensed 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. */
+
+#include "paddle/operators/edit_distance_op.h"
+
+namespace paddle {
+namespace operators {
+
+class EditDistanceOp : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+
+  void InferShape(framework::InferShapeContext *ctx) const override {
+    PADDLE_ENFORCE(ctx->HasInput("Hyps"), "Input(Hyps) shouldn't be null.");
+    PADDLE_ENFORCE(ctx->HasInput("Refs"), "Input(Refs) shouldn't be null.");
+    PADDLE_ENFORCE(ctx->HasOutput("Out"), "Output(Out) shouldn't be null.");
+    auto hyp_dims = ctx->GetInputDim("Hyps");
+    auto ref_dims = ctx->GetInputDim("Refs");
+    PADDLE_ENFORCE(hyp_dims.size() == 2 && hyp_dims[1] == 1,
+                   "Input(Hyps) must be a 2-D LoDTensor with the 2nd dimension "
+                   "equal to 1.");
+    PADDLE_ENFORCE(ref_dims.size() == 2 && ref_dims[1] == 1,
+                   "Input(Refs) must be a 2-D LoDTensor with the 2nd dimension "
+                   "equal to 1.");
+    ctx->SetOutputDim("Out", ctx->GetInputDim("Refs"));
+  }
+
+ protected:
+  framework::OpKernelType GetExpectedKernelType(
+      const framework::ExecutionContext &ctx) const override {
+    return framework::OpKernelType(framework::proto::DataType::FP32,
+                                   ctx.device_context());
+  }
+};
+
+class EditDistanceOpMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  EditDistanceOpMaker(OpProto *proto, OpAttrChecker *op_checker)
+      : OpProtoAndCheckerMaker(proto, op_checker) {
+    AddInput("Hyps",
+             "(2-D LoDTensor<int>, 2nd dim. equal to 1) "
+             "The indices for hypothesis strings.");
+    AddInput("Refs",
+             "(2-D LoDTensor<int>, 2nd dim. equal to 1) "
+             "The indices for reference strings.");
+    AddAttr<bool>("normalized",
+                  "(bool, default false) Indicated whether to normalize "
+                  "the edit distance by the length of reference string.")
+        .SetDefault(false);
+    AddOutput("Out",
+              "(2-D Tensor with shape [`batch_size` x 1]) "
+              "The output edit distances of EditDistance operator.");
+    AddComment(R"DOC(
+
+EditDistance operator computes the edit distances between a batch of hypothesis
+strings and their references.
+
+Edit distance, also called Levenshtein distance, measures how dissimilar two strings 
+are by counting the minimum number of operations to transform one string into anthor. 
+Here the operations include insertion, deletion, and substitution. For example, 
+given hypothesis string A = "kitten" and reference B = "sitting", the edit distance 
+is 3 for A will be transformed into B at least after two substitutions and one 
+insertion:
+  
+   "kitten" -> "sitten" -> "sittin" -> "sitting"
+
+Input(Hyps) is a LoDTensor consisting of all the hypothesis strings with the total 
+number denoted by `batch_size`, and the separation is specified by the LoD information. 
+And the `batch_size` reference strings are arranged in order in the same way in the 
+LoDTensor Input(Refs).
+
+Output(Out) contains the `batch_size` results and each stands for the edit stance 
+for a pair of strings respectively. If Attr(normalized) is true, the edit distance 
+will be divided by the length of reference string.
+)DOC");
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+
+REGISTER_OPERATOR(edit_distance, ops::EditDistanceOp, ops::EditDistanceOpMaker,
+                  paddle::framework::EmptyGradOpMaker);
+REGISTER_OP_CPU_KERNEL(
+    edit_distance, ops::EditDistanceKernel<paddle::platform::CPUPlace, float>);

paddle/operators/edit_distance_op.cu

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+Licensed 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. */
+
+#include <algorithm>
+#include "paddle/framework/op_registry.h"
+#include "paddle/platform/cuda_helper.h"
+#include "paddle/platform/gpu_info.h"
+
+namespace paddle {
+namespace operators {
+
+using platform::PADDLE_CUDA_NUM_THREADS;
+
+template <typename T>
+__global__ void FillFirstRow(T* dist, const int N) {
+  int idx = blockDim.x * blockIdx.x + threadIdx.x;
+  if (idx < N + 1) {
+    dist[idx] = idx;
+  }
+}
+
+template <typename T>
+__global__ void FillFirstColumn(T* dist, const int M, const int N) {
+  int idx = blockDim.x * blockIdx.x + threadIdx.x;
+  if (idx < M + 1) {
+    dist[idx * (N + 1)] = idx;
+  }
+}
+
+template <typename T>
+__global__ void Levenshtein(T* dist, const int* x1, const int* x2, const int M,
+                            const int N, const int start) {
+  int idx = blockDim.x * blockIdx.x + threadIdx.x;
+  int offset = N;
+  int index = start + idx * offset;
+  int row = index / (N + 1);
+  int col = index % (N + 1);
+  if (row > 0 && col > 0 && row < M + 1 && col < N + 1) {
+    int cost = x1[row - 1] == x2[col - 1] ? 0 : 1;
+    int dels = dist[(row - 1) * (N + 1) + col] + 1;
+    int ins = dist[row * (N + 1) + col - 1] + 1;
+    int subs = dist[(row - 1) * (N + 1) + (col - 1)] + cost;
+    dist[index] = min(dels, min(ins, subs));
+  }
+}
+
+template <typename T>
+__global__ void SetOutput(T* out, const T* dist, const int M, const int N,
+                          bool normalized) {
+  int idx = blockDim.x * blockIdx.x + threadIdx.x;
+  if (idx == 0) {
+    out[0] = normalized ? dist[M * (N + 1) + N] / N : dist[M * (N + 1) + N];
+  }
+}
+
+template <typename Place, typename T>
+class EditDistanceGPUKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const {
+    auto* out_t = ctx.Output<framework::Tensor>("Out");
+
+    auto* x1_t = ctx.Input<framework::LoDTensor>("Hyps");
+    auto* x2_t = ctx.Input<framework::LoDTensor>("Refs");
+
+    auto normalized = ctx.Attr<bool>("normalized");
+    auto stream = reinterpret_cast<const platform::CUDADeviceContext&>(
+                      ctx.device_context())
+                      .stream();
+
+    auto hyp_lod = x1_t->lod()[0];
+    auto ref_lod = x2_t->lod()[0];
+    PADDLE_ENFORCE(
+        hyp_lod.size() == ref_lod.size(),
+        "Input(Hyps) and Input(Refs) must have the same batch size.");
+    for (size_t i = 1; i < ref_lod.size(); ++i) {
+      PADDLE_ENFORCE(ref_lod[i] > ref_lod[i - 1],
+                     "Reference string %d is empty.", i);
+    }
+
+    auto num_strs = hyp_lod.size() - 1;
+    out_t->Resize({static_cast<int64_t>(num_strs), 1});
+    out_t->mutable_data<T>(ctx.GetPlace());
+    auto out = out_t->data<T>();
+
+    T distance = 0.0;
+    for (size_t num = 0; num < num_strs; num++) {
+      auto m = static_cast<int64_t>(hyp_lod[num + 1] - hyp_lod[num]);
+      auto n = static_cast<int64_t>(ref_lod[num + 1] - ref_lod[num]);
+      if (m == 0 || n == 0) {
+        distance = std::max(m, n);
+        if (normalized) {
+          PADDLE_ENFORCE(n > 0,
+                         "The reference string (#%d) cannot be empty "
+                         "when Attr(normalized) is enabled.",
+                         n);
+          distance = distance / n;
+        }
+        memory::Copy(boost::get<Place>(ctx.GetPlace()), out + num,
+                     platform::CPUPlace(), &distance, sizeof(T), stream);
+      } else {
+        framework::Tensor dist_t;
+        dist_t.Resize({m + 1, n + 1});
+        dist_t.mutable_data<T>(ctx.GetPlace());
+        auto dist = dist_t.data<T>();
+        auto x1 = x1_t->data<int>() + hyp_lod[num];
+        auto x2 = x2_t->data<int>() + ref_lod[num];
+
+        FillFirstColumn<T><<<1 + m / PADDLE_CUDA_NUM_THREADS,
+                             PADDLE_CUDA_NUM_THREADS, 0, stream>>>(dist, m, n);
+
+        FillFirstRow<T><<<1 + n / PADDLE_CUDA_NUM_THREADS,
+                          PADDLE_CUDA_NUM_THREADS, 0, stream>>>(dist, n);
+        // Compute the elements of distance matrix in the anti-diagonal diretion
+        for (int64_t slice = 2; slice < m + n + 1; ++slice) {
+          int z_m = slice < m + 1 ? 0 : slice - m;
+          int z_n = slice < n + 1 ? 0 : slice - n;
+          int size = slice - (z_m + z_n) + 1;  // number of elments in the same
+                                               // anti-diagonal line to update
+          // the start index at which computes from
+          int start = slice < n + 1 ? slice : (z_n + 1) * (n + 1) - 1;
+          Levenshtein<T><<<1 + (size - 1) / PADDLE_CUDA_NUM_THREADS,
+                           PADDLE_CUDA_NUM_THREADS, 0, stream>>>(dist, x1, x2,
+                                                                 m, n, start);
+        }
+        SetOutput<T><<<1, 1, 0, stream>>>(out + num, dist, m, n, normalized);
+      }
+    }
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+
+REGISTER_OP_CUDA_KERNEL(
+    edit_distance,
+    ops::EditDistanceGPUKernel<paddle::platform::CUDAPlace, float>);

paddle/operators/edit_distance_op.h

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+Licensed 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. */
+
+#pragma once
+#include <algorithm>
+#include "paddle/framework/eigen.h"
+#include "paddle/framework/op_registry.h"
+
+namespace paddle {
+namespace operators {
+
+template <typename Place, typename T>
+class EditDistanceKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const {
+    auto* out_t = ctx.Output<framework::Tensor>("Out");
+
+    auto* x1_t = ctx.Input<framework::LoDTensor>("Hyps");
+    auto* x2_t = ctx.Input<framework::LoDTensor>("Refs");
+
+    auto normalized = ctx.Attr<bool>("normalized");
+
+    auto hyp_lod = x1_t->lod()[0];
+    auto ref_lod = x2_t->lod()[0];
+    PADDLE_ENFORCE(
+        hyp_lod.size() == ref_lod.size(),
+        "Input(Hyps) and Input(Refs) must have the same batch size.");
+    for (size_t i = 1; i < ref_lod.size(); ++i) {
+      PADDLE_ENFORCE(ref_lod[i] > ref_lod[i - 1],
+                     "Reference string %d is empty.", i);
+    }
+    auto num_strs = hyp_lod.size() - 1;
+
+    out_t->Resize({static_cast<int64_t>(num_strs), 1});
+    out_t->mutable_data<float>(ctx.GetPlace());
+    auto out = out_t->data<T>();
+
+    T distance = 0.0;
+    for (size_t num = 0; num < num_strs; ++num) {
+      auto m = static_cast<int64_t>(hyp_lod[num + 1] - hyp_lod[num]);
+      auto n = static_cast<int64_t>(ref_lod[num + 1] - ref_lod[num]);
+
+      if (m == 0) {
+        distance = n;
+      } else if (n == 0) {
+        distance = m;
+      } else {
+        framework::Tensor dist_t;
+        dist_t.Resize({m + 1, n + 1});
+        dist_t.mutable_data<T>(ctx.GetPlace());
+        auto dist = dist_t.data<T>();
+        auto x1 = x1_t->data<int>() + hyp_lod[num];
+        auto x2 = x2_t->data<int>() + ref_lod[num];
+        for (int64_t i = 0; i < m + 1; ++i) {
+          dist[i * (n + 1)] = i;
+        }
+        for (int64_t j = 0; j < n + 1; ++j) {
+          dist[j] = j;
+        }
+        for (int64_t i = 1; i < m + 1; ++i) {
+          for (int64_t j = 1; j < n + 1; ++j) {
+            int cost = x1[i - 1] == x2[j - 1] ? 0 : 1;
+            int dels = dist[(i - 1) * (n + 1) + j] + 1;
+            int ins = dist[i * (n + 1) + (j - 1)] + 1;
+            int subs = dist[(i - 1) * (n + 1) + (j - 1)] + cost;
+            dist[i * (n + 1) + j] = std::min(dels, std::min(ins, subs));
+          }
+        }
+        distance = dist[m * (n + 1) + n];
+      }
+
+      if (normalized) {
+        PADDLE_ENFORCE(n > 0,
+                       "The reference string (#%d) cannot be empty "
+                       "when Attr(normalized) is enabled.",
+                       n);
+        distance = distance / n;
+      }
+      out[num] = distance;
+    }
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle

python/paddle/v2/fluid/tests/test_edit_distance_op.py

+import unittest
+import numpy as np
+from op_test import OpTest
+
+
+def Levenshtein(hyp, ref):
+    """ Compute the Levenshtein distance between two strings.
+
+    :param hyp: hypothesis string in index
+    :type hyp: list
+    :param ref: reference string in index
+    :type ref: list
+    """
+    m = len(hyp)
+    n = len(ref)
+    if m == 0:
+        return n
+    if n == 0:
+        return m
+
+    dist = np.zeros((m + 1, n + 1)).astype("float32")
+    for i in range(0, m + 1):
+        dist[i][0] = i
+    for j in range(0, n + 1):
+        dist[0][j] = j
+
+    for i in range(1, m + 1):
+        for j in range(1, n + 1):
+            cost = 0 if hyp[i - 1] == ref[j - 1] else 1
+            deletion = dist[i - 1][j] + 1
+            insertion = dist[i][j - 1] + 1
+            substitution = dist[i - 1][j - 1] + cost
+            dist[i][j] = min(deletion, insertion, substitution)
+    return dist[m][n]
+
+
+class TestEditDistanceOp(OpTest):
+    def setUp(self):
+        self.op_type = "edit_distance"
+        normalized = False
+        x1 = np.array([[0, 12, 3, 5, 8, 2]]).astype("int32")
+        x2 = np.array([[0, 12, 4, 7, 8]]).astype("int32")
+        x1 = np.transpose(x1)
+        x2 = np.transpose(x2)
+        x1_lod = [0, 1, 5]
+        x2_lod = [0, 3, 4]
+
+        num_strs = len(x1_lod) - 1
+        distance = np.zeros((num_strs, 1)).astype("float32")
+        for i in range(0, num_strs):
+            distance[i] = Levenshtein(
+                hyp=x1[x1_lod[i]:x1_lod[i + 1]],
+                ref=x2[x2_lod[i]:x2_lod[i + 1]])
+            if normalized is True:
+                len_ref = x2_lod[i + 1] - x2_lod[i]
+                distance[i] = distance[i] / len_ref
+        self.attrs = {'normalized': normalized}
+        self.inputs = {'Hyps': (x1, [x1_lod]), 'Refs': (x2, [x2_lod])}
+        self.outputs = {'Out': distance}
+
+    def test_check_output(self):
+        self.check_output()
+
+
+class TestEditDistanceOpNormalized(OpTest):
+    def setUp(self):
+        self.op_type = "edit_distance"
+        normalized = True
+        x1 = np.array([[0, 10, 3, 6, 5, 8, 2]]).astype("int32")
+        x2 = np.array([[0, 10, 4, 6, 7, 8]]).astype("int32")
+        x1 = np.transpose(x1)
+        x2 = np.transpose(x2)
+        x1_lod = [0, 1, 3, 6]
+        x2_lod = [0, 2, 3, 5]
+
+        num_strs = len(x1_lod) - 1
+        distance = np.zeros((num_strs, 1)).astype("float32")
+        for i in range(0, num_strs):
+            distance[i] = Levenshtein(
+                hyp=x1[x1_lod[i]:x1_lod[i + 1]],
+                ref=x2[x2_lod[i]:x2_lod[i + 1]])
+            if normalized is True:
+                len_ref = x2_lod[i + 1] - x2_lod[i]
+                distance[i] = distance[i] / len_ref
+        self.attrs = {'normalized': normalized}
+        self.inputs = {'Hyps': (x1, [x1_lod]), 'Refs': (x2, [x2_lod])}
+        self.outputs = {'Out': distance}
+
+    def test_check_output(self):
+        self.check_output()
+
+
+if __name__ == '__main__':
+    unittest.main()