fullyconnected.cpp

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// File:        fullyconnected.cpp
// Description: Simple feed-forward layer with various non-linearities.
// Author:      Ray Smith
//
// (C) Copyright 2014, Google Inc.
// 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.
 
#ifdef HAVE_CONFIG_H
#  include "config_auto.h"
#endif
 
#include "fullyconnected.h"
 
#ifdef _OPENMP
#  include <omp.h>
#endif
#include <cstdio>
#include <cstdlib>
 
#include "functions.h"
#include "networkscratch.h"
 
// Number of threads to use for parallel calculation of Forward and Backward.
#ifdef _OPENMP
const int kNumThreads = 4;
#else
const int kNumThreads = 1;
#endif
 
namespace tesseract {
 
FullyConnected::FullyConnected(const std::string &name, int ni, int no, NetworkType type)
    : Network(type, name, ni, no), external_source_(nullptr), int_mode_(false) {}
 
// Returns the shape output from the network given an input shape (which may
// be partially unknown ie zero).
StaticShape FullyConnected::OutputShape(const StaticShape &input_shape) const {
  LossType loss_type = LT_NONE;
  if (type_ == NT_SOFTMAX) {
    loss_type = LT_CTC;
  } else if (type_ == NT_SOFTMAX_NO_CTC) {
    loss_type = LT_SOFTMAX;
  } else if (type_ == NT_LOGISTIC) {
    loss_type = LT_LOGISTIC;
  }
  StaticShape result(input_shape);
  result.set_depth(no_);
  result.set_loss_type(loss_type);
  return result;
}
 
// Suspends/Enables training by setting the training_ flag.
void FullyConnected::SetEnableTraining(TrainingState state) {
  if (state == TS_RE_ENABLE) {
    // Enable only from temp disabled.
    if (training_ == TS_TEMP_DISABLE) {
      training_ = TS_ENABLED;
    }
  } else if (state == TS_TEMP_DISABLE) {
    // Temp disable only from enabled.
    if (training_ == TS_ENABLED) {
      training_ = state;
    }
  } else {
    if (state == TS_ENABLED && training_ != TS_ENABLED) {
      weights_.InitBackward();
    }
    training_ = state;
  }
}
 
// Sets up the network for training. Initializes weights using weights of
// scale `range` picked according to the random number generator `randomizer`.
int FullyConnected::InitWeights(float range, TRand *randomizer) {
  Network::SetRandomizer(randomizer);
  num_weights_ = weights_.InitWeightsFloat(no_, ni_ + 1, TestFlag(NF_ADAM), range, randomizer);
  return num_weights_;
}
 
// Recursively searches the network for softmaxes with old_no outputs,
// and remaps their outputs according to code_map. See network.h for details.
 
int FullyConnected::RemapOutputs(int old_no, const std::vector<int> &code_map) {
  if (type_ == NT_SOFTMAX && no_ == old_no) {
    num_weights_ = weights_.RemapOutputs(code_map);
    no_ = code_map.size();
  }
  return num_weights_;
}
 
// Converts a float network to an int network.
void FullyConnected::ConvertToInt() {
  weights_.ConvertToInt();
}
 
// Provides debug output on the weights.
void FullyConnected::DebugWeights() {
  weights_.Debug2D(name_.c_str());
}
 
// Writes to the given file. Returns false in case of error.
bool FullyConnected::Serialize(TFile *fp) const {
  if (!Network::Serialize(fp)) {
    return false;
  }
  if (!weights_.Serialize(IsTraining(), fp)) {
    return false;
  }
  return true;
}
 
// Reads from the given file. Returns false in case of error.
bool FullyConnected::DeSerialize(TFile *fp) {
  return weights_.DeSerialize(IsTraining(), fp);
}
 
// Runs forward propagation of activations on the input line.
// See NetworkCpp for a detailed discussion of the arguments.
void FullyConnected::Forward(bool debug, const NetworkIO &input,
                             const TransposedArray *input_transpose, NetworkScratch *scratch,
                             NetworkIO *output) {
  int width = input.Width();
  if (type_ == NT_SOFTMAX) {
    output->ResizeFloat(input, no_);
  } else {
    output->Resize(input, no_);
  }
  SetupForward(input, input_transpose);
  std::vector<NetworkScratch::FloatVec> temp_lines(kNumThreads);
  std::vector<NetworkScratch::FloatVec> curr_input(kNumThreads);
  int ro = no_;
  if (IntSimdMatrix::intSimdMatrix) {
    ro = IntSimdMatrix::intSimdMatrix->RoundOutputs(ro);
  }
  for (int i = 0; i < kNumThreads; ++i) {
    temp_lines[i].Init(ro, scratch);
    curr_input[i].Init(ni_, scratch);
  }
#ifdef _OPENMP
#  pragma omp parallel for num_threads(kNumThreads)
  for (int t = 0; t < width; ++t) {
    // Thread-local pointer to temporary storage.
    int thread_id = omp_get_thread_num();
#else
  for (int t = 0; t < width; ++t) {
    // Thread-local pointer to temporary storage.
    int thread_id = 0;
#endif
    TFloat *temp_line = temp_lines[thread_id];
    if (input.int_mode()) {
      ForwardTimeStep(input.i(t), t, temp_line);
    } else {
      input.ReadTimeStep(t, curr_input[thread_id]);
      ForwardTimeStep(curr_input[thread_id], t, temp_line);
    }
    output->WriteTimeStep(t, temp_line);
    if (IsTraining() && type_ != NT_SOFTMAX) {
      acts_.CopyTimeStepFrom(t, *output, t);
    }
  }
  // Zero all the elements that are in the padding around images that allows
  // multiple different-sized images to exist in a single array.
  // acts_ is only used if this is not a softmax op.
  if (IsTraining() && type_ != NT_SOFTMAX) {
    acts_.ZeroInvalidElements();
  }
  output->ZeroInvalidElements();
#if DEBUG_DETAIL > 0
  tprintf("F Output:%s\n", name_.c_str());
  output->Print(10);
#endif
#ifndef GRAPHICS_DISABLED
  if (debug) {
    DisplayForward(*output);
  }
#endif
}
 
// Components of Forward so FullyConnected can be reused inside LSTM.
void FullyConnected::SetupForward(const NetworkIO &input, const TransposedArray *input_transpose) {
  // Softmax output is always float, so save the input type.
  int_mode_ = input.int_mode();
  if (IsTraining()) {
    acts_.Resize(input, no_);
    // Source_ is a transposed copy of input. It isn't needed if provided.
    external_source_ = input_transpose;
    if (external_source_ == nullptr) {
      source_t_.ResizeNoInit(ni_, input.Width());
    }
  }
}
 
void FullyConnected::ForwardTimeStep(int t, TFloat *output_line) {
  if (type_ == NT_TANH) {
    FuncInplace<GFunc>(no_, output_line);
  } else if (type_ == NT_LOGISTIC) {
    FuncInplace<FFunc>(no_, output_line);
  } else if (type_ == NT_POSCLIP) {
    FuncInplace<ClipFFunc>(no_, output_line);
  } else if (type_ == NT_SYMCLIP) {
    FuncInplace<ClipGFunc>(no_, output_line);
  } else if (type_ == NT_RELU) {
    FuncInplace<Relu>(no_, output_line);
  } else if (type_ == NT_SOFTMAX || type_ == NT_SOFTMAX_NO_CTC) {
    SoftmaxInPlace(no_, output_line);
  } else if (type_ != NT_LINEAR) {
    ASSERT_HOST("Invalid fully-connected type!" == nullptr);
  }
}
 
void FullyConnected::ForwardTimeStep(const TFloat *d_input, int t, TFloat *output_line) {
  // input is copied to source_ line-by-line for cache coherency.
  if (IsTraining() && external_source_ == nullptr) {
    source_t_.WriteStrided(t, d_input);
  }
  weights_.MatrixDotVector(d_input, output_line);
  ForwardTimeStep(t, output_line);
}
 
void FullyConnected::ForwardTimeStep(const int8_t *i_input, int t, TFloat *output_line) {
  // input is copied to source_ line-by-line for cache coherency.
  weights_.MatrixDotVector(i_input, output_line);
  ForwardTimeStep(t, output_line);
}
 
// Runs backward propagation of errors on the deltas line.
// See NetworkCpp for a detailed discussion of the arguments.
bool FullyConnected::Backward(bool debug, const NetworkIO &fwd_deltas, NetworkScratch *scratch,
                              NetworkIO *back_deltas) {
#ifndef GRAPHICS_DISABLED
  if (debug) {
    DisplayBackward(fwd_deltas);
  }
#endif
  back_deltas->Resize(fwd_deltas, ni_);
  std::vector<NetworkScratch::FloatVec> errors(kNumThreads);
  for (int i = 0; i < kNumThreads; ++i) {
    errors[i].Init(no_, scratch);
  }
  std::vector<NetworkScratch::FloatVec> temp_backprops;
  if (needs_to_backprop_) {
    temp_backprops.resize(kNumThreads);
    for (int i = 0; i < kNumThreads; ++i) {
      temp_backprops[i].Init(ni_, scratch);
    }
  }
  int width = fwd_deltas.Width();
  NetworkScratch::GradientStore errors_t;
  errors_t.Init(no_, width, scratch);
#ifdef _OPENMP
#  pragma omp parallel for num_threads(kNumThreads)
  for (int t = 0; t < width; ++t) {
    int thread_id = omp_get_thread_num();
#else
  for (int t = 0; t < width; ++t) {
    int thread_id = 0;
#endif
    TFloat *backprop = nullptr;
    if (needs_to_backprop_) {
      backprop = temp_backprops[thread_id];
    }
    TFloat *curr_errors = errors[thread_id];
    BackwardTimeStep(fwd_deltas, t, curr_errors, errors_t.get(), backprop);
    if (backprop != nullptr) {
      back_deltas->WriteTimeStep(t, backprop);
    }
  }
  FinishBackward(*errors_t.get());
  if (needs_to_backprop_) {
    back_deltas->ZeroInvalidElements();
#if DEBUG_DETAIL > 0
    tprintf("F Backprop:%s\n", name_.c_str());
    back_deltas->Print(10);
#endif
    return true;
  }
  return false; // No point going further back.
}
 
void FullyConnected::BackwardTimeStep(const NetworkIO &fwd_deltas, int t, TFloat *curr_errors,
                                      TransposedArray *errors_t, TFloat *backprop) {
  if (type_ == NT_TANH) {
    acts_.FuncMultiply<GPrime>(fwd_deltas, t, curr_errors);
  } else if (type_ == NT_LOGISTIC) {
    acts_.FuncMultiply<FPrime>(fwd_deltas, t, curr_errors);
  } else if (type_ == NT_POSCLIP) {
    acts_.FuncMultiply<ClipFPrime>(fwd_deltas, t, curr_errors);
  } else if (type_ == NT_SYMCLIP) {
    acts_.FuncMultiply<ClipGPrime>(fwd_deltas, t, curr_errors);
  } else if (type_ == NT_RELU) {
    acts_.FuncMultiply<ReluPrime>(fwd_deltas, t, curr_errors);
  } else if (type_ == NT_SOFTMAX || type_ == NT_SOFTMAX_NO_CTC || type_ == NT_LINEAR) {
    fwd_deltas.ReadTimeStep(t, curr_errors); // fwd_deltas are the errors.
  } else {
    ASSERT_HOST("Invalid fully-connected type!" == nullptr);
  }
  // Generate backprop only if needed by the lower layer.
  if (backprop != nullptr) {
    weights_.VectorDotMatrix(curr_errors, backprop);
  }
  errors_t->WriteStrided(t, curr_errors);
}
 
void FullyConnected::FinishBackward(const TransposedArray &errors_t) {
  if (external_source_ == nullptr) {
    weights_.SumOuterTransposed(errors_t, source_t_, true);
  } else {
    weights_.SumOuterTransposed(errors_t, *external_source_, true);
  }
}
 
// Updates the weights using the given learning rate, momentum and adam_beta.
// num_samples is used in the adam computation iff use_adam_ is true.
void FullyConnected::Update(float learning_rate, float momentum, float adam_beta, int num_samples) {
  weights_.Update(learning_rate, momentum, adam_beta, num_samples);
}
 
// Sums the products of weight updates in *this and other, splitting into
// positive (same direction) in *same and negative (different direction) in
// *changed.
void FullyConnected::CountAlternators(const Network &other, TFloat *same, TFloat *changed) const {
  ASSERT_HOST(other.type() == type_);
  const auto *fc = static_cast<const FullyConnected *>(&other);
  weights_.CountAlternators(fc->weights_, same, changed);
}
 
} // namespace tesseract.