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NetAppend[net,layer]

appends a layer or a net onto a NetChain, a layer or a NetGraph with one output port.

NetAppend[net,"name"layer]

appends a layer with a given name.

NetAppend[net,{layer1,layer2,…}]

appends several layers or nets.

Details and Options
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Options  
"Input"  
"Output"  
Possible Issues  
See Also
Tech Notes
Related Guides
History
Cite this Page

NetAppend

NetAppend[net,layer]

appends a layer or a net onto a NetChain, a layer or a NetGraph with one output port.

NetAppend[net,"name"layer]

appends a layer with a given name.

NetAppend[net,{layer1,layer2,…}]

appends several layers or nets.

Details and Options

  • The input of the appended layer must be compatible with the output of the final layer in the chain.
  • Any NetDecoder previously attached to the end of net will be removed.
  • NetAppend takes the following options:
  • "Input"Automatictype for the input of the resulting chain
    "Output"Automatictype for the output of the resulting chain
  • Options "Input" and "Output" support the normal type specifications allowed by NetChain, including NetEncoder and NetDecoder.

Examples

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Basic Examples  (3)

Append a layer to the end of a chain:

Wolfram Language code: NetAppend[NetChain[{1, Tanh, 3}], SoftmaxLayer[]]

Append a named layer to the end of a chain:

Wolfram Language code: NetAppend[NetChain[<|"A" -> 1, "B" -> Tanh, "C" -> 3|>], "D" -> SoftmaxLayer[]]

Append several layers to the end of a chain:

Wolfram Language code: NetAppend[NetChain[{1, Tanh, 3}], {Tanh, 5, SoftmaxLayer[]}]

Scope  (3)

Append a layer and attach a NetDecoder:

Wolfram Language code: NetAppend[NetChain[{1, Tanh, 3}], SoftmaxLayer[], "Output" -> NetDecoder["Class"]]

Create a NetChain with NetAppend:

Wolfram Language code: NetAppend[LinearLayer[], Ramp]

Append a layer to a NetGraph with one output:

Wolfram Language code: ng = NetGraph[{1, 2, Plus}, {{NetPort["Foo"] -> 1, NetPort["Bar"] -> 2} -> 3}]
Wolfram Language code: NetAppend[ng, SummationLayer[]]

Append a named layer:

Wolfram Language code: NetAppend[ng, "Sum" -> SummationLayer[]]

Options  (6)

"Input"  (3)

Set the input shape of the net:

Wolfram Language code: NetAppend[NetChain[{1, Tanh, 3}], SoftmaxLayer[], "Input" -> {3}]

Set a NetEncoder for the net:

Wolfram Language code: NetAppend[NetChain[{1, Tanh, 3}], SoftmaxLayer[], "Input" -> NetEncoder[{"Class", {x, y, z}}]]

Using this option is equivalent to using NetReplacePart on the returned net:

Wolfram Language code: net = NetAppend[NetChain[{1, Tanh, 3}], SoftmaxLayer[]]
Wolfram Language code: NetReplacePart[net, "Input" -> NetEncoder[{"Class", {x, y, z}}]]

"Output"  (3)

Set a NetDecoder for the net:

Wolfram Language code: NetAppend[NetChain[{1, Tanh, 3}], SoftmaxLayer[], "Output" -> NetDecoder[{"Class", {x, y, z}}]]

Using this option is equivalent to using NetReplacePart on the returned net:

Wolfram Language code: net = NetAppend[NetChain[{1, Tanh, 3}], SoftmaxLayer[]]
Wolfram Language code: NetReplacePart[net, "Output" -> NetDecoder[{"Class", {x, y, z}}]]

An existing NetDecoder can be added back to the returned net using this option, provided it is compatible with the new final layer:

Wolfram Language code: dec = NetDecoder[{"Class", {x, y, z}}]
Wolfram Language code: net = NetChain[{1, Tanh, 3}, "Output" -> dec]
Wolfram Language code: NetAppend[net, SoftmaxLayer[]]
Wolfram Language code: NetAppend[net, SoftmaxLayer[], "Output" -> dec]

Possible Issues  (3)

The input of the appended layer must be compatible with the output of the final layer in the chain:

Wolfram Language code: NetAppend[NetChain[{1, 2, 3}], PoolingLayer[{3}]]

A layer with several input ports cannot be appended:

Wolfram Language code: NetAppend[NetChain[{1, 2, 3}], AttentionLayer[]]

A layer cannot be appended to a network with more than one output:

Wolfram Language code: ng = NetGraph[{1, 2}, {}]
Wolfram Language code: NetAppend[ng, LinearLayer[]]
Wolfram Research (2018), NetAppend, Wolfram Language function, https://reference.wolfram.com/language/ref/NetAppend.html (updated 2021).

Text

Wolfram Research (2018), NetAppend, Wolfram Language function, https://reference.wolfram.com/language/ref/NetAppend.html (updated 2021).

CMS

Wolfram Language. 2018. "NetAppend." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2021. https://reference.wolfram.com/language/ref/NetAppend.html.

APA

Wolfram Language. (2018). NetAppend. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/NetAppend.html

BibTeX

@misc{reference.wolfram_2026_netappend, author="Wolfram Research", title="{NetAppend}", year="2021", howpublished="\url{https://reference.wolfram.com/language/ref/NetAppend.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_netappend, organization={Wolfram Research}, title={NetAppend}, year={2021}, url={https://reference.wolfram.com/language/ref/NetAppend.html}, note=[Accessed: 13-June-2026]}