---
title: ParameterVector (latest version)
description: API reference for qiskit.circuit.ParameterVector in the latest version of qiskit
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/qiskit.circuit.ParameterVector
---

# ParameterVector

*class* `qiskit.circuit.ParameterVector(name, length=0, uuid=None)`

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

A container of many related [`Parameter`](/docs/api/qiskit/qiskit.circuit.Parameter "qiskit.circuit.Parameter") objects.

This class is faster to construct than constructing many [`Parameter`](/docs/api/qiskit/qiskit.circuit.Parameter "qiskit.circuit.Parameter") objects individually, and the individual names of the parameters will all share a common stem (the name of the vector). For a vector called `v` with length 3, the individual elements will have names `v[0]`, `v[1]` and `v[2]`.

The elements of a vector are sorted by the name of the vector, then the numeric value of their index.

This class fulfills the [`collections.abc.Sequence`](https://docs.python.org/3/library/collections.abc.html#collections.abc.Sequence) interface.

## Attributes

### name

The base name of the vector.

### params

A sequence of the contained [`ParameterVectorElement`](/docs/api/qiskit/qiskit.circuit.ParameterVectorElement "qiskit.circuit.ParameterVectorElement") instances.

Mutations to this object are not tracked.

### uuid

Get the root UUID of this vector.

## Methods

### index

`index(val)`

Find the index of a [`ParameterVectorElement`](/docs/api/qiskit/qiskit.circuit.ParameterVectorElement "qiskit.circuit.ParameterVectorElement") within the sequence.

This is an inefficient way of accessing the [`index`](/docs/api/qiskit/qiskit.circuit.ParameterVectorElement#index "qiskit.circuit.ParameterVectorElement.index") field on the given value, which you should use instead.

### resize

`resize(length)`

Change the length of this vector.

Any references to [`ParameterVectorElement`](/docs/api/qiskit/qiskit.circuit.ParameterVectorElement "qiskit.circuit.ParameterVectorElement") instances with lengths greater than `length` are invalidated by calling this.

The UUIDs of [`ParameterVectorElement`](/docs/api/qiskit/qiskit.circuit.ParameterVectorElement "qiskit.circuit.ParameterVectorElement") instances that are deleted or created by this method are stable; the UUIDs are always derived as index offsets from the vector’s UUID.