---
title: ParameterVector (v1.2)
description: API reference for qiskit.circuit.ParameterVector in qiskit v1.2
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/1.2/qiskit.circuit.ParameterVector
---

# ParameterVector

*class* `qiskit.circuit.ParameterVector(name, length=0)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/circuit/parametervector.py#L50-L120)

Bases: [`object`](https://docs.python.org/3/library/functions.html#object)

ParameterVector class to quickly generate lists of parameters.

## Attributes

### name

Returns the name of the ParameterVector.

### params

Returns the list of parameters in the ParameterVector.

## Methods

### index

`index(value)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/circuit/parametervector.py#L73-L75)

Returns first index of value.

### resize

`resize(length)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/circuit/parametervector.py#L92-L120)

Resize the parameter vector. If necessary, new elements are generated.

Note that the UUID of each [`Parameter`](/docs/api/qiskit/1.2/qiskit.circuit.Parameter "qiskit.circuit.Parameter") element will be generated deterministically given the root UUID of the `ParameterVector` and the index of the element. In particular, if a `ParameterVector` is resized to be smaller and then later resized to be larger, the UUID of the later generated element at a given index will be the same as the UUID of the previous element at that index. This is to ensure that the parameter instances do not change.

```python
>>> from qiskit.circuit import ParameterVector
>>> pv = ParameterVector("theta", 20)
>>> elt_19 = pv[19]
>>> rv.resize(10)
>>> rv.resize(20)
>>> pv[19] == elt_19
True
```