source/application/main/Classifier.cc

/*
 * Copyright (c) 2021 Arm Limited. All rights reserved.
 * SPDX-License-Identifier: Apache-2.0
 *
 * 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 "Classifier.hpp"

#include "hal.h"
#include "TensorFlowLiteMicro.hpp"

#include <vector>
#include <string>
#include <set>
#include <cstdint>
#include <inttypes.h>
#include "PlatformMath.hpp"

namespace arm {
namespace app {

    void Classifier::SetVectorResults(std::set<std::pair<float, uint32_t>>& topNSet,
                          std::vector<ClassificationResult>& vecResults,
                          const std::vector <std::string>& labels)
    {

        /* Reset the iterator to the largest element - use reverse iterator. */

        auto topNIter = topNSet.rbegin();
        for (size_t i = 0; i < vecResults.size() && topNIter != topNSet.rend(); ++i, ++topNIter) {
            vecResults[i].m_normalisedVal = topNIter->first;
            vecResults[i].m_label = labels[topNIter->second];
            vecResults[i].m_labelIdx = topNIter->second;
        }
    }

    bool Classifier::GetTopNResults(const std::vector<float>& tensor,
                                    std::vector<ClassificationResult>& vecResults,
                                    uint32_t topNCount,
                                    const std::vector <std::string>& labels)
    {

        std::set<std::pair<float , uint32_t>> sortedSet;

        /* NOTE: inputVec's size verification against labels should be
         *       checked by the calling/public function. */

        /* Set initial elements. */
        for (uint32_t i = 0; i < topNCount; ++i) {
            sortedSet.insert({tensor[i], i});
        }

        /* Initialise iterator. */
        auto setFwdIter = sortedSet.begin();

        /* Scan through the rest of elements with compare operations. */
        for (uint32_t i = topNCount; i < labels.size(); ++i) {
            if (setFwdIter->first < tensor[i]) {
                sortedSet.erase(*setFwdIter);
                sortedSet.insert({tensor[i], i});
                setFwdIter = sortedSet.begin();
            }
        }

        /* Final results' container. */
        vecResults = std::vector<ClassificationResult>(topNCount);
        SetVectorResults(sortedSet, vecResults, labels);

        return true;
    }

    bool  Classifier::GetClassificationResults(
        TfLiteTensor* outputTensor,
        std::vector<ClassificationResult>& vecResults,
        const std::vector <std::string>& labels,
        uint32_t topNCount,
        bool useSoftmax)
    {
        if (outputTensor == nullptr) {
            printf_err("Output vector is null pointer.\n");
            return false;
        }

        uint32_t totalOutputSize = 1;
        for (int inputDim = 0; inputDim < outputTensor->dims->size; inputDim++) {
            totalOutputSize *= outputTensor->dims->data[inputDim];
        }

        /* Sanity checks. */
        if (totalOutputSize < topNCount) {
            printf_err("Output vector is smaller than %" PRIu32 "\n", topNCount);
            return false;
        } else if (totalOutputSize != labels.size()) {
            printf_err("Output size doesn't match the labels' size\n");
            return false;
        } else if (topNCount == 0) {
            printf_err("Top N results cannot be zero\n");
            return false;
        }

        bool resultState;
        vecResults.clear();

        /* De-Quantize Output Tensor */
        QuantParams quantParams = GetTensorQuantParams(outputTensor);

        /* Floating point tensor data to be populated
         * NOTE: The assumption here is that the output tensor size isn't too
         * big and therefore, there's neglibible impact on heap usage. */
        std::vector<float> tensorData(totalOutputSize);

        /* Populate the floating point buffer */
        switch (outputTensor->type) {
            case kTfLiteUInt8: {
                uint8_t *tensor_buffer = tflite::GetTensorData<uint8_t>(outputTensor);
                for (size_t i = 0; i < totalOutputSize; ++i) {
                    tensorData[i] = quantParams.scale *
                        (static_cast<float>(tensor_buffer[i]) - quantParams.offset);
                }
                break;
            }
            case kTfLiteInt8: {
                int8_t *tensor_buffer = tflite::GetTensorData<int8_t>(outputTensor);
                for (size_t i = 0; i < totalOutputSize; ++i) {
                    tensorData[i] = quantParams.scale *
                        (static_cast<float>(tensor_buffer[i]) - quantParams.offset);
                }
                break;
            }
            case kTfLiteFloat32: {
                float *tensor_buffer = tflite::GetTensorData<float>(outputTensor);
                for (size_t i = 0; i < totalOutputSize; ++i) {
                    tensorData[i] = tensor_buffer[i];
                }
                break;
            }
            default:
                printf_err("Tensor type %s not supported by classifier\n",
                    TfLiteTypeGetName(outputTensor->type));
                return false;
        }

        if (useSoftmax) {
            math::MathUtils::SoftmaxF32(tensorData);
        }

        /* Get the top N results. */
        resultState = GetTopNResults(tensorData, vecResults, topNCount, labels);

        if (!resultState) {
            printf_err("Failed to get top N results set\n");
            return false;
        }

        return true;
    }
} /* namespace app */
} /* namespace arm */