qiskit.transpiler.PassManager

class PassManager(passes=None, max_iteration=1000, callback=None)

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Manager for a set of Passes and their scheduling during transpilation.

Initialize an empty PassManager object (with no passes scheduled).

Parameters

passes (Union[BasePass, List[BasePass], None]) – A pass set (as defined in qiskit.transpiler.PassManager.append()) to be added to the pass manager schedule.
max_iteration (int) – The maximum number of iterations the schedule will be looped if the condition is not met.
callback (Optional[Callable]) – DEPRECATED - A callback function that will be called after each pass execution.

Deprecated since version 0.13.0

The callback parameter is deprecated in favor of PassManager.run(..., callback=callback, ...).

init

__init__(passes=None, max_iteration=1000, callback=None)

Initialize an empty PassManager object (with no passes scheduled).

Parameters

passes (Union[BasePass, List[BasePass], None]) – A pass set (as defined in qiskit.transpiler.PassManager.append()) to be added to the pass manager schedule.
max_iteration (int) – The maximum number of iterations the schedule will be looped if the condition is not met.
callback (Optional[Callable]) – DEPRECATED - A callback function that will be called after each pass execution.

Deprecated since version 0.13.0

The callback parameter is deprecated in favor of PassManager.run(..., callback=callback, ...).

Methods


`__init__`([passes, max_iteration, callback])	Initialize an empty PassManager object (with no passes scheduled).
`append`(passes[, max_iteration])	Append a Pass Set to the schedule of passes.
`draw`([filename, style, raw])	Draw the pass manager.
`passes`()	Return a list structure of the appended passes and its options.
`remove`(index)	Removes a particular pass in the scheduler.
`replace`(index, passes[, max_iteration])	Replace a particular pass in the scheduler.
`run`(circuits[, output_name, callback])	Run all the passes on the specified `circuits`.

append

append(passes, max_iteration=None, **flow_controller_conditions)

Append a Pass Set to the schedule of passes.

Parameters

passes (Union[BasePass, List[BasePass]]) – A set of passes (a pass set) to be added to schedule. A pass set is a list of passes that are controlled by the same flow controller. If a single pass is provided, the pass set will only have that pass a single element.
max_iteration (Optional[int]) – max number of iterations of passes.
flow_controller_conditions (Any) – control flow plugins.

Raises

TranspilerError – if a pass in passes is not a proper pass.

draw

draw(filename=None, style=None, raw=False)

Draw the pass manager.

This function needs pydot, which in turn needs Graphviz to be installed.

Parameters

filename (str) – file path to save image to.
style (dict) – keys are the pass classes and the values are the colors to make them. An example can be seen in the DEFAULT_STYLE. An ordered dict can be used to ensure a priority coloring when pass falls into multiple categories. Any values not included in the provided dict will be filled in from the default dict.
raw (bool) – If True, save the raw Dot output instead of the image.

Returns

an in-memory representation of the pass manager, or None if no image was generated or Pillow is not installed.

Return type

Optional[PassManager]

Raises

ImportError – when nxpd or pydot not installed.

passes

passes()

Return a list structure of the appended passes and its options.

Return type

List[Dict[str, BasePass]]

Returns

A list of pass sets, as defined in append().

remove

remove(index)

Removes a particular pass in the scheduler.

Parameters

index (int) – Pass index to replace, based on the position in passes().

Raises

TranspilerError – if the index is not found.

Return type

None

replace

replace(index, passes, max_iteration=None, **flow_controller_conditions)

Replace a particular pass in the scheduler.

Parameters

index (int) – Pass index to replace, based on the position in passes().
passes (Union[BasePass, List[BasePass]]) – A pass set (as defined in qiskit.transpiler.PassManager.append()) to be added to the pass manager schedule.
max_iteration (Optional[int]) – max number of iterations of passes.
flow_controller_conditions (Any) – control flow plugins.

Raises

TranspilerError – if a pass in passes is not a proper pass or index not found.

run

run(circuits, output_name=None, callback=None)

Run all the passes on the specified circuits.

Parameters

circuits (Union[QuantumCircuit, List[QuantumCircuit]]) – Circuit(s) to transform via all the registered passes.
output_name (Optional[str]) – The output circuit name. If None, it will be set to the same as the input circuit name.
callback (Optional[Callable]) –

A callback function that will be called after each pass execution. The function will be called with 5 keyword arguments:
```
pass_ (Pass): the pass being run
dag (DAGCircuit): the dag output of the pass
time (float): the time to execute the pass
property_set (PropertySet): the property set
count (int): the index for the pass execution
```
The exact arguments pass expose the internals of the pass manager and are subject to change as the pass manager internals change. If you intend to reuse a callback function over multiple releases be sure to check that the arguments being passed are the same.

To use the callback feature you define a function that will take in kwargs dict and access the variables. For example:
```
def callback_func(**kwargs):
    pass_ = kwargs['pass_']
    dag = kwargs['dag']
    time = kwargs['time']
    property_set = kwargs['property_set']
    count = kwargs['count']
    ...
```

Return type

Union[QuantumCircuit, List[QuantumCircuit]]

Returns

The transformed circuit(s).

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