formatLayer

R2026b

Format layer

Since R2026b

Description

A format layer applies a data format to its input data.

Creation

Syntax

layer = formatLayer(fmt)

layer = formatLayer(fmt,Name=name)

Description

layer = formatLayer(fmt) creates a format layer that applies the specified data format to the layer input.

layer = formatLayer(fmt,Name=name) also sets the optional Name property using a name-value argument.

Input Arguments

fmt — Description of the data dimensions

character vector | string scalar

Description of the data dimensions, specified as a character vector or string scalar that represents a deep learning data format.

A deep learning data format is a string of characters, where each character describes the type of the corresponding data dimension. The characters are:

• "S" — Spatial

• "C" — Channel

• "B" — Batch

• "T" — Time

• "U" — Unspecified

For example, suppose you have an array that represents a batch of sequences where the first, second, and third dimensions correspond to channels, observations, and time steps, respectively. You can describe the data as having the format "CBT" (channel, batch, time).

You can specify multiple dimensions labeled "S" or "U". You can use the labels "C", "B", and "T" at most once each. The software ignores singleton trailing "U" dimensions after the second dimension.

To remove the data format from the data, specify fmt as "".

The number of dimension labels must be greater than or equal to the number of dimensions in the layer input data. If the number of labels is greater than the number of input dimensions, then the layer introduces additional singleton dimensions.

For more information, see Deep Learning Data Formats.

This argument sets the DataFormat property.

Data Types: char | string

name — Layer name

"" (default) | character vector | string scalar

Layer name, specified as a character vector or a string scalar. For Layer array input, the trainnet and dlnetwork functions automatically assign names to unnamed layers.

This argument sets the Name property.

Data Types: char | string

Properties

Format

DataFormat — Data format

character vector

This property is read-only after object creation. To set this property, use the corresponding positional input argument when you create the FormatLayer object.

Description of the data dimensions, represented as a character vector or string scalar that represents a deep learning data format.

A deep learning data format is a string of characters, where each character describes the type of the corresponding data dimension. The characters are:

• "S" — Spatial

• "C" — Channel

• "B" — Batch

• "T" — Time

• "U" — Unspecified

For example, suppose you have an array that represents a batch of sequences where the first, second, and third dimensions correspond to channels, observations, and time steps, respectively. You can describe the data as having the format "CBT" (channel, batch, time).

If the number of labels is greater than the number of input dimensions, then the layer introduces additional singleton dimensions.

If DataFormat is '', then the layer removes the data format from the data.

For more information, see Deep Learning Data Formats.

Data Types: char

Layer

Name — Layer name

'' (default) | character vector

Layer name, specified as a character vector. For Layer array input, the trainnet and dlnetwork functions automatically assign names to unnamed layers.

Data Types: char

NumInputs — Number of inputs

Read-only: 1 (default)

This property is read-only.

Number of inputs to the layer, represented as 1. This layer has a single input only.

Data Types: double

InputNames — Input name

Read-only: {'in'} (default)

This property is read-only.

Input name, represented as {'in'}. This layer has a single input only.

NumOutputs — Number of outputs

Read-only: 1 (default)

This property is read-only.

Number of outputs from the layer, represented as 1. This layer has a single output only.

Data Types: double

OutputNames — Output name

Read-only: {'out'} (default)

This property is read-only.

Output name, represented as {'out'}. This layer has a single output only.

Examples

Create Format Layer

Create a format layer that applies the data format "SCB" (spatial, channel, batch) to its input.

layer = formatLayer("SCB")

layer = 
  FormatLayer with properties:

          Name: ''
    DataFormat: 'SCB'

   Hyperparameters
    No properties.

Algorithms

Layer Input and Output Formats

Most 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 format consists of one or more of these characters:

• "S" — Spatial

• "C" — Channel

• "B" — Batch

• "T" — Time

• "U" — Unspecified

For example, you can describe 2-D image data that is 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, as having the format "SSCB" (spatial, spatial, channel, batch).

FormatLayer objects support input data of any format. The layer applies the data format specified by the DataFormat property to the layer input. When DataFormat is "", the layer removes the data format from the input, producing unformatted output.

For more information, see Deep Learning Data Formats.

Complex Numbers

FormatLayer objects support complex-valued input and outputs. The layer applies the same underlying operation to complex-valued input as it does to real-valued input. The layer outputs complex-valued data where applicable.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Version History

Introduced in R2026b