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2026-07-13 12:40:42 +08:00

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// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
//
// 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/phi/kernels/edit_distance_kernel.h"
#include "paddle/phi/backends/cpu/cpu_context.h"
#include "paddle/phi/core/kernel_registry.h"
#include "paddle/phi/core/mixed_vector.h"
#include "paddle/phi/kernels/funcs/eigen/common.h"
namespace phi {
template <typename T, typename Context>
void EditDistanceKernel(const Context& dev_ctx,
const DenseTensor& hyps,
const DenseTensor& refs,
const optional<DenseTensor>& hypslength,
const optional<DenseTensor>& refslength,
bool normalized,
DenseTensor* sequencenum,
DenseTensor* out) {
int64_t* seq_num_data = dev_ctx.template Alloc<int64_t>(sequencenum);
auto batch_size = hyps.dims()[0];
Vector<size_t> hyp_lod(batch_size + 1);
Vector<size_t> ref_lod(batch_size + 1);
bool use_length = hypslength.get_ptr() != nullptr;
if (use_length) {
// build lod when using padding
auto hyp_length_ptr = hypslength.get_ptr()->data<int64_t>();
auto ref_length_ptr = refslength.get_ptr()->data<int64_t>();
for (auto i = 0; i < batch_size; i++) {
hyp_lod[i + 1] = hyp_lod[i] + hyp_length_ptr[i];
ref_lod[i + 1] = ref_lod[i] + ref_length_ptr[i];
}
} else {
hyp_lod = hyps.lod()[0];
ref_lod = refs.lod()[0];
}
if (normalized) {
for (size_t i = 1; i < ref_lod.size(); ++i) {
PADDLE_ENFORCE_GT(
ref_lod[i],
ref_lod[i - 1],
errors::InvalidArgument("Reference string %d is empty.", i));
}
}
auto num_strs = hyp_lod.size() - 1;
*seq_num_data = static_cast<int64_t>(num_strs);
out->Resize({static_cast<int64_t>(num_strs), 1});
dev_ctx.template Alloc<T>(out);
auto outdata = out->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 {
DenseTensor dist_t;
dist_t.Resize({m + 1, n + 1});
dev_ctx.template Alloc<T>(&dist_t);
auto dist = dist_t.data<T>();
auto hyp_offset = use_length ? num * hyps.dims()[1] : hyp_lod[num];
auto ref_offset = use_length ? num * refs.dims()[1] : ref_lod[num];
auto x1 = hyps.data<int64_t>() + hyp_offset;
auto x2 = refs.data<int64_t>() + ref_offset;
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_GT(
n,
0UL,
errors::InvalidArgument("The reference string (#%d) cannot be empty "
"when Attr(normalized) is enabled.",
n));
distance = distance / n;
}
outdata[num] = distance;
}
}
} // namespace phi
PD_REGISTER_KERNEL(
edit_distance, CPU, ALL_LAYOUT, phi::EditDistanceKernel, float) {
kernel->OutputAt(0).SetDataType(phi::DataType::INT64);
}