library(keras) knitr::opts_chunk$set(comment = NA, eval = FALSE)
Keras layers are the fundamental building block of keras models. Layers are created using a wide variety of layer_ functions and are typically composed together by stacking calls to them using the pipe %>% operator. For example:
model <- keras_model_sequential() model %>% layer_dense(units = 32, input_shape = c(784)) %>% layer_activation('relu') %>% layer_dense(units = 10) %>% layer_activation('softmax')
A wide variety of layers are available, including:
All layers share the following properties:
layer$name --- String, must be unique within a model.
layer$input_spec --- List of input specifications. Each entry describes one required input: (ndim, dtype). A layer with n input tensors must have an input_spec of length n.
layer$trainable --- Boolean, whether the layer weights will be updated during training.
layer$uses_learning_phase -- Whether any operation of the layer uses K.in_training_phase() or K.in_test_phase().
layer$input_shape --- Input shape. Provided for convenience, but note that there may be cases in which this
attribute is ill-defined (e.g. a shared layer with multiple input shapes), in which case
requesting input_shape will result in an error. Prefer using get_input_shape_at(layer, node_index).
layer$output_shape --- Output shape. See above.
layer$inbound_nodes --- List of nodes.
layer$outbound_nodes --- List of nodes.
layer$input, layer$output --- Input/output tensor(s). Note that if the layer is used more than
once (shared layer), this is ill-defined and will result in an error. In such cases, use get_input_at(layer, node_index).
layer$input_mask, layer$output_mask --- Same as above, for masks.
layer$trainable_weights --- List of variables.
layer$non_trainable_weights --- List of variables.
layer$weights --- The concatenation of the lists trainable_weights and
non_trainable_weights (in this order).
layer$constraints --- Mapping of weights to constraints.
The following functions are available for interacting with layers:
| `get_config()` `from_config()` | Layer/Model configuration |
| `get_weights()` `set_weights()` | Layer/Model weights as R arrays |
| `count_params()` | Count the total number of scalars composing the weights. |
| `get_input_at()` `get_output_at()` `get_input_shape_at()` `get_output_shape_at()` `get_input_mask_at()` `get_output_mask_at()` | Retrieve tensors for layers with multiple nodes |
| `reset_states()` | Reset the states for a layer |
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