Layers in a layer array or layer graph pass data to subsequent layers as formatted dlarray
objects. The format of a dlarray
object is a string of characters, in which each character describes the corresponding dimension of the data. The formats consists of one or more of these characters:
"S"
— Spatial
"C"
— Channel
"B"
— Batch
"T"
— Time
"U"
— Unspecified
For example, 2-D image data represented as a 4-D array, where the first two dimensions correspond to the spatial dimensions of the images, the third dimension corresponds to the channels of the images, and the fourth dimension corresponds to the batch dimension, can be described as having the format "SSCB"
(spatial, spatial, channel, batch).
You can interact with these dlarray
objects in automatic differentiation workflows such as developing a custom layer, using a functionLayer
object, or using the forward
and predict
functions with dlnetwork
objects.
This table shows the supported input formats of DepthConcatenationLayer
objects and the
corresponding output format. If the software passes the output of the layer to a custom
layer that does not inherit from the nnet.layer.Formattable
class, or a
FunctionLayer
object with the Formattable
property
set to 0
(false), then the layer receives an unformatted
dlarray
object with dimensions ordered corresponding to the formats in
this table. The formats listed here are only a subset. The layer may support additional
formats such as formats with additional "S"
(spatial) or
"U"
(unspecified) dimensions.
The output format matches the input format.
Input Format | Output Format |
---|
"SSCB" (spatial, spatial, channel,
batch)
| "SSCB" (spatial, spatial, channel,
batch)
|
"SSSCB" (spatial, spatial, spatial,
channel, batch)
| "SSSCB" (spatial, spatial, spatial,
channel, batch)
|
"SSCBT" (spatial, spatial, channel,
batch, time)
| "SSCBT" (spatial, spatial, channel,
batch, time)
|
"SSSCBT" (spatial, spatial, spatial,
channel, batch, time)
| "SSSCBT" (spatial, spatial, spatial,
channel, batch, time)
|
"SSC" (spatial, spatial,
channel)
| "SSC" (spatial, spatial,
channel)
|
"SSSC" (spatial, spatial, spatial,
channel)
| "SSSC" (spatial, spatial, spatial,
channel)
|
In dlnetwork
objects, DepthConcatenationLayer
objects also
support these input and output format combinations.
Input Format | Output Format |
---|
"SSCT" (spatial, spatial, channel,
time)
| "SSCT" (spatial, spatial, channel,
time)
|
"SSSCT" (spatial, spatial, spatial,
channel, time)
| "SSSCT" (spatial, spatial, spatial,
channel, time)
|