124 lines
4.5 KiB
Plaintext
124 lines
4.5 KiB
Plaintext
---
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title: Options
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description: API reference for qiskit.providers.Options
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in_page_toc_min_heading_level: 1
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python_api_type: class
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python_api_name: qiskit.providers.Options
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---
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# Options
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<Class id="qiskit.providers.Options" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.24/qiskit/providers/options.py" signature="Options(**kwargs)" modifiers="class">
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Bases: `Mapping`
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Base options object
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This class is what all backend options are based on. The properties of the class are intended to be all dynamically adjustable so that a user can reconfigure the backend on demand. If a property is immutable to the user (eg something like number of qubits) that should be a configuration of the backend class itself instead of the options.
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Instances of this class behave like dictionaries. Accessing an option with a default value can be done with the get() method:
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```python
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>>> options = Options(opt1=1, opt2=2)
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>>> options.get("opt1")
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1
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>>> options.get("opt3", default="hello")
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'hello'
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```
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Key-value pairs for all options can be retrieved using the items() method:
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```python
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>>> list(options.items())
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[('opt1', 1), ('opt2', 2)]
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```
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Options can be updated by name:
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```python
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>>> options["opt1"] = 3
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>>> options.get("opt1")
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3
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```
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Runtime validators can be registered. See set\_validator. Updates through update\_options and indexing (\_\_setitem\_\_) validate the new value before peforming the update and raise ValueError if the new value is invalid.
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```python
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>>> options.set_validator("opt1", (1, 5))
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>>> options["opt1"] = 4
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>>> options["opt1"]
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4
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>>> options["opt1"] = 10
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Traceback (most recent call last):
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...
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ValueError: ...
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```
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## Methods
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<span id="qiskit-providers-options-get" />
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### get
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<Function id="qiskit.providers.Options.get" signature="Options.get(k[, d]) → D[k] if k in D, else d. d defaults to None." />
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<span id="qiskit-providers-options-items" />
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### items
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<Function id="qiskit.providers.Options.items" signature="Options.items() → a set-like object providing a view on D's items" />
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<span id="qiskit-providers-options-keys" />
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### keys
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<Function id="qiskit.providers.Options.keys" signature="Options.keys() → a set-like object providing a view on D's keys" />
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<span id="qiskit-providers-options-set-validator" />
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### set\_validator
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<Function id="qiskit.providers.Options.set_validator" signature="Options.set_validator(field, validator_value)">
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Set an optional validator for a field in the options
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Setting a validator enables changes to an options values to be validated for correctness when [`update_options()`](qiskit.providers.Options#update_options "qiskit.providers.Options.update_options") is called. For example if you have a numeric field like `shots` you can specify a bounds tuple that set an upper and lower bound on the value such as:
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```python
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options.set_validator("shots", (1, 4096))
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```
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In this case whenever the `"shots"` option is updated by the user it will enforce that the value is >=1 and \<=4096. A `ValueError` will be raised if it’s outside those bounds. If a validator is already present for the specified field it will be silently overriden.
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**Parameters**
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* **field** (*str*) – The field name to set the validator on
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* **validator\_value** (*list or tuple or type*) – The value to use for the validator depending on the type indicates on how the value for a field is enforced. If a tuple is passed in it must have a length of two and will enforce the min and max value (inclusive) for an integer or float value option. If it’s a list it will list the valid values for a field. If it’s a `type` the validator will just enforce the value is of a certain type.
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**Raises**
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* **KeyError** – If field is not present in the options object
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* **ValueError** – If the `validator_value` has an invalid value for a given type
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* **TypeError** – If `validator_value` is not a valid type
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</Function>
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<span id="qiskit-providers-options-update-options" />
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### update\_options
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<Function id="qiskit.providers.Options.update_options" signature="Options.update_options(**fields)">
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Update options with kwargs
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</Function>
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<span id="qiskit-providers-options-values" />
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### values
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<Function id="qiskit.providers.Options.values" signature="Options.values() → an object providing a view on D's values" />
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## Attributes
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### validator
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<Attribute id="qiskit.providers.Options.validator" />
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</Class>
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