Class Layer

include/singa/model/layer.h:37–222

The base layer class. Generally, a layer conducts feature transformation against a set of Tensor to generate a set of Tensor. Each layer may have some parameters.

/// Generally, a layer conducts feature transformation against a set of Tensor
/// to generate a set of Tensor. Each layer may have some parameters.
class Layer {
 public:
  Layer() = default;

  /// Set meta data fields from a string representing a proto message.
  /// 'in_shape' is the shape of the input feature for one sample
  void Setup(const Shape& in_shape, const string& proto_str) {
    LayerConf conf;
    conf.ParseFromString(proto_str);
    this->Setup(in_shape, conf);
  }

  /// 'in_shapes' is the shape of the input feature for one sample
  void Setup(const vector<Shape>& in_shapes, const string& proto_str) {
    LayerConf conf;
    conf.ParseFromString(proto_str);
    this->Setup(in_shapes, conf);
  }


  // ============= Following Functions could be override =====================
  /// Destruct objects created by this layer.
  virtual ~Layer() {};

  /// Each layer sub-class would optionaly have a type name.
  /// Used for debugging and logging.
  virtual const std::string layer_type() const { return "Unknown"; }

  /// Set meta data fields configured in 'conf' (a proto message).
  /// Some layers would use input tensor shapes for setting its parameter
  /// shapes (e.g, desen layer and convolution layer). 'in_shape' provides such
  /// shape info. It represents the shape of the Tensor (with a single sample)
  /// from the last layer.
  /// After calling Setup, the shape info of parameters should be accssed
  /// correctly. Internal buffer/fields are set assuming batchsize is 1.
  virtual void Setup(const Shape& in_sample, const LayerConf& conf) {
    name_ = conf.name();
    // TODO(wangwei) load param values from checkpoint files.
  }

  /// Used for layers that have multiple input tensors, e.g., concatenate layer.
  virtual void Setup(const vector<Shape>& in_samples, const LayerConf& conf) {
    name_ = conf.name();
    // TODO(wangwei) load param values from checkpoint files.
  }

  /// Return the shape of the generated Tensor without the batchsize dimension
  virtual const Shape GetOutputSampleShape() const {
    LOG(FATAL) << "Pls override this function";
    return vector<size_t>{};
  }
  /// Return the shape of the k-th generated tensor without the batchsize
  /// dimension. Used for layers that generate multiple tensors.
  virtual const Shape GetOutputSampleShape(int k) {
    LOG(FATAL) << "Pls override this function";
    return vector<size_t>{};
  }