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PartLayer[i]

represents a net layer that gives the i^(th) part of the input.

PartLayer[i;;j]

gives parts i through j.

PartLayer[i;;j;;k]

gives parts i through j in steps of k.

PartLayer[{spec1,spec2,…}]

takes part speci at level i in the input.

Details and Options
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Arguments  
Ports  
Possible Issues  
See Also
Tech Notes
Related Guides
History
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PartLayer

PartLayer[i]

represents a net layer that gives the i^(th) part of the input.

PartLayer[i;;j]

gives parts i through j.

PartLayer[i;;j;;k]

gives parts i through j in steps of k.

PartLayer[{spec1,spec2,…}]

takes part speci at level i in the input.

Details and Options

  • PartLayer[…][input] explicitly computes the output from applying the layer to input.
  • PartLayer[…][{input1,input2,…}] explicitly computes outputs for each of the inputi.
  • PartLayer exposes the following ports for use in NetGraph etc.:
  • "Input"an array
    "Output"an array
  • PartLayer is typically used inside NetChain, NetGraph, etc.
  • PartLayer normally infers the dimensions of its input from its context in NetChain etc. To specify the dimensions explicitly as {n1,n2,…}, use PartLayer["Input"->{n1,n2,…}].
  • PartLayer[i;;j] and PartLayer[i;;j;;k] give an output that is of the same rank as the input, whereas PartLayer[i] gives an output that is one rank smaller.
  • Information[PartLayer[…]] gives a report about the layer.
  • Information[PartLayer[…],prop] gives the value of the property prop of PartLayer[…]. Possible properties are the same as for NetGraph.

Examples

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Basic Examples  (2)

Create a PartLayer that takes the second part of an array:

Wolfram Language code: PartLayer[2]

Create a PartLayer that takes the second part of an array:

Wolfram Language code: p = PartLayer[2]

Apply the layer to a vector:

Wolfram Language code: p[{1, 2, 3, 4, 5, 6}]

Scope  (6)

Arguments  (3)

Create a PartLayer that takes the first two elements:

Wolfram Language code: p = PartLayer[1 ;; 2]

Apply the layer to a matrix:

Wolfram Language code: p[{{1, 2}, {3, 4}, {5, 6}}]

Create a PartLayer that takes the next-to-last element in an array:

Wolfram Language code: p = PartLayer[-2]

Apply the layer to a vector:

Wolfram Language code: p[{1, 2, 3, 4, 5, 6}]

Create a PartLayer that takes all elements after the second one:

Wolfram Language code: p = PartLayer[2 ;; ]

Apply the layer to a vector:

Wolfram Language code: p[{-1, -2, -3, -4, -5}]

This is equivalent to using All:

Wolfram Language code: PartLayer[2 ;; All][{-1, -2, -3, -4, -5}]

Ports  (3)

Create a PartLayer whose inputs are vectors of length three:

Wolfram Language code: p = PartLayer[2, "Input" -> 3]

The layer threads across a batch of examples:

Wolfram Language code: p[{{1, 2, 3}, {0.1, 0.2, 0.3}}]

Create a PartLayer that takes the first column of its input, which is a matrix:

Wolfram Language code: p = PartLayer[{All, 1}, "Input" -> {2, 3}]

Apply the layer to a matrix:

Wolfram Language code: p[{{1, 2, 3}, {4, 5, 6}}]

Create a PartLayer that takes numbers at an odd place:

Wolfram Language code: p = PartLayer[ ;; ;; 2, "Input" -> {Automatic}]

Apply the layer to a list of numbers:

Wolfram Language code: p[Range[10]]

Possible Issues  (1)

Using Part with a Span where the second index is smaller than the first is valid syntax, producing an empty list:

Wolfram Language code: {1, 2, 3, 4}[[3 ;; 2]]

This is invalid syntax for PartLayer, as empty arrays are not allowed in nets:

Wolfram Language code: PartLayer[3 ;; 2]
Wolfram Research (2017), PartLayer, Wolfram Language function, https://reference.wolfram.com/language/ref/PartLayer.html (updated 2021).

Text

Wolfram Research (2017), PartLayer, Wolfram Language function, https://reference.wolfram.com/language/ref/PartLayer.html (updated 2021).

CMS

Wolfram Language. 2017. "PartLayer." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2021. https://reference.wolfram.com/language/ref/PartLayer.html.

APA

Wolfram Language. (2017). PartLayer. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/PartLayer.html

BibTeX

@misc{reference.wolfram_2026_partlayer, author="Wolfram Research", title="{PartLayer}", year="2021", howpublished="\url{https://reference.wolfram.com/language/ref/PartLayer.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_partlayer, organization={Wolfram Research}, title={PartLayer}, year={2021}, url={https://reference.wolfram.com/language/ref/PartLayer.html}, note=[Accessed: 13-June-2026]}