ai.onnx.ReverseSequence
ai.onnx · standard ONNX operator · ONNX opset ≥ 10
Description
Reverses variable-length sequences in a batch along a time axis. For each batch slice i, the first sequence_lens[i] elements along time_axis are reversed in place; elements beyond that length are copied unchanged. The output has the same shape as the input.
See the ONNX ReverseSequence spec for the reference semantics.
Inputs
| Name | Bind key | Logical dtype | WebGPU storage | Rank | Shape | Description | Presence |
|---|---|---|---|---|---|---|---|
input |
input |
T |
runtime-selected; narrow integers and bool use 32-bit slots | — | — | Input tensor of rank 2 or greater containing the batch of sequences to reverse. | required |
sequence_lens |
sequence_lens |
I |
uint32 |
1 |
— | Logical int64 1-D tensor of shape [batch_size] specifying each non-negative sequence length; WebGPU stores it as uint32. |
required |
Outputs
| Name | Bind key | Logical dtype | Rank | Shape | Description | Presence |
|---|---|---|---|---|---|---|
Y |
y |
T |
same as input |
same as input |
Output tensor with the same shape as the input, with each sequence reversed up to its specified length. | required |
Attributes
Default values (overridable per request):
| Attribute | Default | Description |
|---|---|---|
batch_axis |
1 |
Axis that represents the batch dimension; must be 0 or 1 (default 1). |
time_axis |
0 |
Axis that represents the time/sequence dimension to be reversed; must be 0 or 1 (default 0). |
Type constraints
| Variable | Allowed dtypes |
|---|---|
T |
float32, float16, uint32, int32, int16, uint8, int8, bool |
I |
int64 |
Files
metadata.json— kernel metadata (id, digests, provenance)manifest.json— the op contract (source of truth)test.json— correctness casesbench.json— benchmark + tuning casesreverse-sequence-vec4.wgsl.jinjareverse-sequence.wgsl.jinja
Use with @huggingface/kernels
The loader derives every required output's shape and logical dtype from the manifest contract and this call. It then allocates the result tensors automatically.
The version: 1 option selects the published kernel contract; it is independent of any operator opset, contrib since_version, or model version.
Replace each *Data placeholder with a typed array containing the corresponding input data.
import { getKernel } from "@huggingface/kernels";
const kernel = await getKernel("webgpu-kernels/ai.onnx.ReverseSequence", { version: 1 });
const { y } = await kernel({
input: { data: inputData, shape: [4, 2, 1] },
sequence_lens: { data: sequence_lensData, shape: [2] },
});
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Requires WebGPU support. See the compatibility table.