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SequenceIndicesLayer[]

represents a net layer that produces a list of indices for an input sequence.

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

SequenceIndicesLayer

SequenceIndicesLayer[]

represents a net layer that produces a list of indices for an input sequence.

Details and Options

  • SequenceIndicesLayer[…] takes a sequence of arrays and outputs a sequence of integers of the same length.
  • SequenceIndicesLayer is typically used inside NetChain, NetGraph, etc.
  • The following optional parameter can be included:
  • "Maximum" Infinitymaximum index to output
  • SequenceIndicesLayer["Maximum"max] corresponds to the function Min[max,Range[Length[#]]]&.
  • The input and output ports of the net represented by SequenceIndicesLayer[] are:
  • "Input"a sequence of n arrays
    "Output"a sequence of n arrays
  • SequenceIndicesLayer["Input"shape] allows the shape of the input to be specified. Possible forms for shape include:
  • na sequence of n numbers
    "Varying"a sequence of numbers of varying length
    {len,d1,d2,…}sequence of len arrays of dimensions d1×d2×…
    {"Varying",d1,d2,…}varying number of arrays of dimensions d1×d2×…
  • Options[SequenceIndicesLayer] gives the list of default options to construct the layer. Options[SequenceIndicesLayer[…]] gives the list of default options to evaluate the layer on some data.
  • Information[SequenceIndicesLayer[…]] gives a report about the layer.
  • Information[SequenceIndicesLayer[…],prop] gives the value of the property prop of SequenceIndicesLayer[…]. Possible properties are the same as for NetGraph.

Examples

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Basic Examples  (1)

Create a SequenceIndicesLayer that expects a sequence of vectors of size 3:

Wolfram Language code: indices = SequenceIndicesLayer["Input" -> {"Varying", 3}]

Apply the layer to a sequence of vectors:

Wolfram Language code: indices[RandomReal[1, {4, 3}]]

Scope  (2)

Ports  (2)

Create a SequenceIndicesLayer that expects a length-3 sequence of 2x2 matrices:

Wolfram Language code: ind = SequenceIndicesLayer["Input" -> {3, 2, 2}]

Apply the layer to a sequence:

Wolfram Language code: ind[{{{1, 2}, {4, 5}}, {{7, 8}, {10, 11}}, {{12, 13}, {14, 15}}}]

Create a SequenceIndicesLayer that expects a sequence of real numbers:

Wolfram Language code: ind = SequenceIndicesLayer["Input" -> "Varying"]

Thread the layer across a batch of inputs:

Wolfram Language code: ind[{{1, 2, 3}, {4, 5}, {6, 7, 8, 9}}]

Options  (1)

"Maximum"  (1)

Create a SequenceIndicesLayer that returns a maximum index of 3:

Wolfram Language code: indices = SequenceIndicesLayer["Maximum" -> 3]

Apply the layer to a sequence:

Wolfram Language code: indices[RandomReal[1, {7, 10}]]

Possible Issues  (1)

SequenceIndicesLayer cannot accept symbolic inputs:

Wolfram Language code: indices = SequenceIndicesLayer[]; indices[{1, 2}]
Wolfram Language code: indices[{1, z}]
Wolfram Research (2021), SequenceIndicesLayer, Wolfram Language function, https://reference.wolfram.com/language/ref/SequenceIndicesLayer.html.

Text

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

CMS

Wolfram Language. 2021. "SequenceIndicesLayer." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/SequenceIndicesLayer.html.

APA

Wolfram Language. (2021). SequenceIndicesLayer. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/SequenceIndicesLayer.html

BibTeX

@misc{reference.wolfram_2026_sequenceindiceslayer, author="Wolfram Research", title="{SequenceIndicesLayer}", year="2021", howpublished="\url{https://reference.wolfram.com/language/ref/SequenceIndicesLayer.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_sequenceindiceslayer, organization={Wolfram Research}, title={SequenceIndicesLayer}, year={2021}, url={https://reference.wolfram.com/language/ref/SequenceIndicesLayer.html}, note=[Accessed: 13-June-2026]}