---
title: SliceRegisterNode (latest version)
description: API reference for samplomatic.samplex.nodes.SliceRegisterNode in the latest version of samplomatic
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/samplomatic/auto/samplex-nodes-slice-register-node
---

# SliceRegisterNode

*class* `samplomatic.samplex.nodes.SliceRegisterNode(input_type: VirtualType, output_type: VirtualType, input_register_name: str, output_register_name: str, slice_idxs: slice | Sequence[int], force_copy: bool = False)`

[GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/samplex/nodes/slice_register_node.py#L26-L144)

Bases: [`EvaluationNode`](/docs/api/samplomatic/auto/samplex-nodes-evaluation-node "samplomatic.samplex.nodes.evaluation_node.EvaluationNode")

A node to slice a register.

> **Note**
>
> Slicing of a register can alternatively be done using a [`CombineRegistersNode`](/docs/api/samplomatic/auto/samplex-nodes-combine-registers-node "samplomatic.samplex.nodes.CombineRegistersNode"), providing `operands` of length `1`. However, using [`SliceRegisterNode`](#samplomatic.samplex.nodes.SliceRegisterNode "samplomatic.samplex.nodes.SliceRegisterNode") is recommended because its [`evaluate()`](#samplomatic.samplex.nodes.SliceRegisterNode.evaluate "samplomatic.samplex.nodes.SliceRegisterNode.evaluate") method is optimized for slicing a single register.

**Parameters**

- **input\_type** – The type of the input register.
- **output\_type** – The type of the output register.
- **input\_register\_name** – The name of the input register.
- **output\_register\_name** – The name of the output register.
- **slice\_idxs** – The indices used to slice the register.
- **force\_copy** – Whether or not to force output register to be a copy instead of a view of the input register.

**Raises**

[**SamplexConstructionError**](/docs/api/samplomatic/auto/exceptions-samplex-construction-error "samplomatic.exceptions.SamplexConstructionError") – If `slice_idxs` has the wrong shape.

**Attributes Summary**

|                                                                                                                                                                      |                                              |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------- |
| [`outgoing_register_type`](#samplomatic.samplex.nodes.SliceRegisterNode.outgoing_register_type "samplomatic.samplex.nodes.SliceRegisterNode.outgoing_register_type") | The virtual gate type of outgoing registers. |

**Methods Summary**

|                                                                                                                                                                                     |                                                                                  |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------- |
| [`evaluate`](#samplomatic.samplex.nodes.SliceRegisterNode.evaluate "samplomatic.samplex.nodes.SliceRegisterNode.evaluate")(registers, \*\_)                                         | Evaluate this node.                                                              |
| [`get_style`](#samplomatic.samplex.nodes.SliceRegisterNode.get_style "samplomatic.samplex.nodes.SliceRegisterNode.get_style")()                                                     | Return the style of this node when plotted.                                      |
| [`instantiates`](#samplomatic.samplex.nodes.SliceRegisterNode.instantiates "samplomatic.samplex.nodes.SliceRegisterNode.instantiates")()                                            | Return a manifest of new virtual registers that this node instantiates.          |
| [`reads_from`](#samplomatic.samplex.nodes.SliceRegisterNode.reads_from "samplomatic.samplex.nodes.SliceRegisterNode.reads_from")()                                                  | Return a manifest of which virtual register values this node needs to read from. |
| [`validate_and_update`](#samplomatic.samplex.nodes.SliceRegisterNode.validate_and_update "samplomatic.samplex.nodes.SliceRegisterNode.validate_and_update")(register\_descriptions) | Validate provided register descriptions are compatible, update with changes.     |

**Attributes Documentation**

### outgoing\_register\_type

**Methods Documentation**

### evaluate

`evaluate(registers, *_)`

[GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/samplex/nodes/slice_register_node.py#L117-L119)

Evaluate this node.

**Parameters**

- **registers** – At least those registers needed by this node to read from or write to.
- **parameter\_values** – Parameter values to use during evaluation.

**Raises**

[**SamplexRuntimeError**](/docs/api/samplomatic/auto/exceptions-samplex-runtime-error "samplomatic.exceptions.SamplexRuntimeError") – If the number of parameter values received does not equal the number required by this node.

### get\_style

`get_style()`

[GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/samplex/nodes/slice_register_node.py#L137-L144)

Return the style of this node when plotted.

### instantiates

`instantiates()`

[GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/samplex/nodes/slice_register_node.py#L81-L92)

Return a manifest of new virtual registers that this node instantiates.

> **Note**
>
> - To change the type or size of a register, both instantiate and remove it.
> - Do not specify [`reads_from()`](#samplomatic.samplex.nodes.SliceRegisterNode.reads_from "samplomatic.samplex.nodes.SliceRegisterNode.reads_from") or `writes_to()` for an instantiated register, these powers are implicit.

### reads\_from

`reads_from()`

[GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/samplex/nodes/slice_register_node.py#L94-L105)

Return a manifest of which virtual register values this node needs to read from.

### validate\_and\_update

`validate_and_update(register_descriptions)`

[GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/samplex/nodes/slice_register_node.py#L107-L115)

Validate provided register descriptions are compatible, update with changes.

This method can be used by a samplex to determine when a node execution order has well-defined dependencies before sampling begins.

**Parameters**

**register\_descriptions** – A map from existing register names to their size and type.