---
title: BaseEstimator (v1.3)
description: API reference for qiskit.primitives.BaseEstimator in qiskit v1.3
source: https://quantum.cloud.ibm.com/docs/en/api/qiskit/1.3/qiskit.primitives.BaseEstimator
---

# BaseEstimator

*class* `qiskit.primitives.BaseEstimator(*, options=None)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/primitives/base/base_estimator.py#L191-L217)

Bases: [`BaseEstimatorV1`](/docs/api/qiskit/1.3/qiskit.primitives.BaseEstimatorV1 "qiskit.primitives.base.base_estimator.BaseEstimatorV1")\[`T`]

DEPRECATED. Type alias for Estimator V1 base class.

See [`BaseEstimatorV1`](/docs/api/qiskit/1.3/qiskit.primitives.BaseEstimatorV1 "qiskit.primitives.BaseEstimatorV1") for details.

Creating an instance of an Estimator, or using one in a `with` context opens a session that holds resources until the instance is `close()` ed or the context is exited.

> **Deprecated since version 1.2**
>
> The class `qiskit.primitives.base.base_estimator.BaseEstimator` is deprecated as of qiskit 1.2. It will be removed no earlier than 3 months after the release date. The BaseEstimator class is a type alias for the BaseEstimatorV1 interface that has been deprecated in favor of explicitly versioned interface classes. It is recommended to migrate all implementations to use BaseEstimatorV2. However, for implementations incompatible with BaseEstimatorV2, BaseEstimator can be replaced with the explicitly versioned BaseEstimatorV1 class.

**Parameters**

**options** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict) *| None*) – Default options.

## Attributes

### options

Return options values for the estimator.

**Returns**

options

## Methods

### run

`run(circuits, observables, parameter_values=None, **run_options)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/primitives/base/base_estimator.py#L121-L178)

Run the job of the estimation of expectation value(s).

`circuits`, `observables`, and `parameter_values` should have the same length. The i-th element of the result is the expectation of observable

```python
obs = observables[i]
```

for the state prepared by

```python
circ = circuits[i]
```

with bound parameters

```python
values = parameter_values[i]
```

**Parameters**

- **circuits** (*Sequence\[*[*QuantumCircuit*](/docs/api/qiskit/1.3/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")*] |* [*QuantumCircuit*](/docs/api/qiskit/1.3/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")) – one or more circuit objects.
- **observables** (*Sequence\[BaseOperator |* [*str*](https://docs.python.org/3/library/stdtypes.html#str)*] | BaseOperator |* [*str*](https://docs.python.org/3/library/stdtypes.html#str)) – one or more observable objects. Several formats are allowed; importantly, `str` should follow the string representation format for [`Pauli`](/docs/api/qiskit/1.3/qiskit.quantum_info.Pauli "qiskit.quantum_info.Pauli") objects.
- **parameter\_values** (*Sequence\[Sequence\[*[*float*](https://docs.python.org/3/library/functions.html#float)*]] | Sequence\[*[*float*](https://docs.python.org/3/library/functions.html#float)*] |* [*float*](https://docs.python.org/3/library/functions.html#float) *| None*) – concrete parameters to be bound.
- **run\_options** – runtime options used for circuit execution.

**Returns**

The job object of EstimatorResult.

**Raises**

- [**TypeError**](https://docs.python.org/3/library/exceptions.html#TypeError) – Invalid argument type given.
- [**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError) – Invalid argument values given.

**Return type**

T

### set\_options

`set_options(**fields)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.3/qiskit/primitives/base/base_primitive.py#L39-L45)

Set options values for the estimator.

**Parameters**

**\*\*fields** – The fields to update the options