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---
title: PassManager
description: API reference for qiskit.transpiler.PassManager
in_page_toc_min_heading_level: 1
python_api_type: class
python_api_name: qiskit.transpiler.PassManager
---
# PassManager
<Class id="qiskit.transpiler.PassManager" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.21/qiskit/transpiler/passmanager.py" signature="PassManager(passes=None, max_iteration=1000)" modifiers="class">
Bases: `object`
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()`](qiskit.transpiler.PassManager#append "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.
## Methods
### append
<Function id="qiskit.transpiler.PassManager.append" signature="PassManager.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. It is also possible to append a [`FlowController`](qiskit.transpiler.FlowController "qiskit.transpiler.runningpassmanager.FlowController") instance and the rest of the parameter will be ignored.
* **max\_iteration** (`Optional`\[`int`]) max number of iterations of passes.
* **flow\_controller\_conditions** (`Any`) control flow plugins.
**Raises**
[**TranspilerError**](qiskit.transpiler.TranspilerError "qiskit.transpiler.TranspilerError") if a pass in passes is not a proper pass.
<Admonition title="See also" type="note">
`RunningPassManager.add_flow_controller()` for more information about the control flow plugins.
</Admonition>
**Return type**
`None`
</Function>
### draw
<Function id="qiskit.transpiler.PassManager.draw" signature="PassManager.draw(filename=None, style=None, raw=False)">
Draw the pass manager.
This function needs [pydot](https://github.com/erocarrera/pydot), which in turn needs [Graphviz](https://www.graphviz.org/) 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](https://pypi.org/project/Pillow/) is not installed.
**Return type**
Optional\[[PassManager](qiskit.transpiler.PassManager "qiskit.transpiler.PassManager")]
**Raises**
**ImportError** when nxpd or pydot not installed.
</Function>
### passes
<Function id="qiskit.transpiler.PassManager.passes" signature="PassManager.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()`.
</Function>
### remove
<Function id="qiskit.transpiler.PassManager.remove" signature="PassManager.remove(index)">
Removes a particular pass in the scheduler.
**Parameters**
**index** (`int`) Pass index to replace, based on the position in passes().
**Raises**
[**TranspilerError**](qiskit.transpiler.TranspilerError "qiskit.transpiler.TranspilerError") if the index is not found.
**Return type**
`None`
</Function>
### replace
<Function id="qiskit.transpiler.PassManager.replace" signature="PassManager.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()`](qiskit.transpiler.PassManager#append "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**](qiskit.transpiler.TranspilerError "qiskit.transpiler.TranspilerError") if a pass in passes is not a proper pass or index not found.
<Admonition title="See also" type="note">
`RunningPassManager.add_flow_controller()` for more information about the control flow plugins.
</Admonition>
**Return type**
`None`
</Function>
### run
<Function id="qiskit.transpiler.PassManager.run" signature="PassManager.run(circuits, output_name=None, callback=None)">
Run all the passes on the specified `circuits`.
**Parameters**
* **circuits** (`Union`\[[`QuantumCircuit`](qiskit.circuit.QuantumCircuit "qiskit.circuit.quantumcircuit.QuantumCircuit"), `List`\[[`QuantumCircuit`](qiskit.circuit.QuantumCircuit "qiskit.circuit.quantumcircuit.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:
```python
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:
```python
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`](qiskit.circuit.QuantumCircuit "qiskit.circuit.quantumcircuit.QuantumCircuit"), `List`\[[`QuantumCircuit`](qiskit.circuit.QuantumCircuit "qiskit.circuit.quantumcircuit.QuantumCircuit")]]
**Returns**
The transformed circuit(s).
</Function>
</Class>