---
title: ScheduleBlock (v1.1)
description: API reference for qiskit.pulse.ScheduleBlock in qiskit v1.1
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/1.1/qiskit.pulse.ScheduleBlock
---

# ScheduleBlock

*class* `qiskit.pulse.ScheduleBlock(name=None, metadata=None, alignment_context=None)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L827-L1624)

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

Time-ordered sequence of instructions with alignment context.

[`ScheduleBlock`](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock") supports lazy scheduling of context instructions, i.e. their timeslots is always generated at runtime. This indicates we can parametrize instruction durations as well as other parameters. In contrast to [`Schedule`](/docs/api/qiskit/1.1/qiskit.pulse.Schedule "qiskit.pulse.Schedule") being somewhat static, [`ScheduleBlock`](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock") is a dynamic representation of a pulse program.

**Pulse Builder**

The Qiskit pulse builder is a domain specific language that is developed on top of the schedule block. Use of the builder syntax will improve the workflow of pulse programming. See [Pulse Builder](/docs/api/qiskit/1.1/pulse#pulse-builder) for a user guide.

**Alignment contexts**

A schedule block is always relatively scheduled. Instead of taking individual instructions with absolute execution time `t0`, the schedule block defines a context of scheduling and instructions under the same context are scheduled in the same manner (alignment). Several contexts are available in [Alignments](/docs/api/qiskit/1.1/pulse#pulse-alignments). A schedule block is instantiated with one of these alignment contexts. The default context is `AlignLeft`, for which all instructions are left-justified, in other words, meaning they use as-soon-as-possible scheduling.

If you need an absolute-time interval in between instructions, you can explicitly insert [`Delay`](/docs/api/qiskit/1.1/qiskit.pulse.instructions.Delay "qiskit.pulse.instructions.Delay") instructions.

**Nested blocks**

A schedule block can contain other nested blocks with different alignment contexts. This enables advanced scheduling, where a subset of instructions is locally scheduled in a different manner. Note that a [`Schedule`](/docs/api/qiskit/1.1/qiskit.pulse.Schedule "qiskit.pulse.Schedule") instance cannot be directly added to a schedule block. To add a [`Schedule`](/docs/api/qiskit/1.1/qiskit.pulse.Schedule "qiskit.pulse.Schedule") instance, wrap it in a `Call` instruction. This is implicitly performed when a schedule is added through the [Pulse Builder](/docs/api/qiskit/1.1/pulse#pulse-builder).

**Unsupported operations**

Because the schedule block representation lacks timeslots, it cannot perform particular [`Schedule`](/docs/api/qiskit/1.1/qiskit.pulse.Schedule "qiskit.pulse.Schedule") operations such as `insert()` or `shift()` that require instruction start time `t0`. In addition, [`exclude()`](#qiskit.pulse.ScheduleBlock.exclude "qiskit.pulse.ScheduleBlock.exclude") and [`filter()`](#qiskit.pulse.ScheduleBlock.filter "qiskit.pulse.ScheduleBlock.filter") methods are not supported because these operations may identify the target instruction with `t0`. Except for these operations, [`ScheduleBlock`](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock") provides full compatibility with [`Schedule`](/docs/api/qiskit/1.1/qiskit.pulse.Schedule "qiskit.pulse.Schedule").

**Subroutine**

The timeslots-free representation offers much greater flexibility for writing pulse programs. Because [`ScheduleBlock`](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock") only cares about the ordering of the child blocks we can add an undefined pulse sequence as a subroutine of the main program. If your program contains the same sequence multiple times, this representation may reduce the memory footprint required by the program construction. Such a subroutine is realized by the special compiler directive [`Reference`](/docs/api/qiskit/1.1/qiskit.pulse.instructions.Reference "qiskit.pulse.instructions.Reference") that is defined by a unique set of reference key strings to the subroutine. The (executable) subroutine is separately stored in the main program. Appended reference directives are resolved when the main program is executed. Subroutines must be assigned through [`assign_references()`](#qiskit.pulse.ScheduleBlock.assign_references "qiskit.pulse.ScheduleBlock.assign_references") before execution.

One way to reference a subroutine in a schedule is to use the pulse builder’s [`reference()`](/docs/api/qiskit/1.1/pulse#qiskit.pulse.builder.reference "qiskit.pulse.builder.reference") function to declare an unassigned reference. In this example, the program is called with the reference key “grand\_child”. You can call a subroutine without specifying a substantial program.

```python
from qiskit import pulse
from qiskit.circuit.parameter import Parameter

amp1 = Parameter("amp1")
amp2 = Parameter("amp2")

with pulse.build() as sched_inner:
    pulse.play(pulse.Constant(100, amp1), pulse.DriveChannel(0))

with pulse.build() as sched_outer:
    with pulse.align_right():
        pulse.reference("grand_child")
        pulse.play(pulse.Constant(200, amp2), pulse.DriveChannel(0))
```

Now you assign the inner pulse program to this reference.

```python
sched_outer.assign_references({("grand_child", ): sched_inner})
print(sched_outer.parameters)
```

```python
{Parameter(amp1), Parameter(amp2)}
```

The outer program now has the parameter `amp2` from the inner program, indicating that the inner program’s data has been made available to the outer program. The program calling the “grand\_child” has a reference program description which is accessed through [`ScheduleBlock.references`](#qiskit.pulse.ScheduleBlock.references "qiskit.pulse.ScheduleBlock.references").

```python
print(sched_outer.references)
```

```python
ReferenceManager:
  - ('grand_child',): ScheduleBlock(Play(Constant(duration=100, amp=amp1,...
```

Finally, you may want to call this program from another program. Here we try a different approach to define subroutine. Namely, we call a subroutine from the root program with the actual program `sched2`.

```python
amp3 = Parameter("amp3")

with pulse.build() as main:
    pulse.play(pulse.Constant(300, amp3), pulse.DriveChannel(0))
    pulse.call(sched_outer, name="child")

print(main.parameters)
```

```python
{Parameter(amp1), Parameter(amp2), Parameter(amp3}
```

This implicitly creates a reference named “child” within the root program and assigns `sched_outer` to it.

Note that the root program is only aware of its direct references.

```python
print(main.references)
```

```python
ReferenceManager:
  - ('child',): ScheduleBlock(ScheduleBlock(ScheduleBlock(Play(Con...
```

As you can see the main program cannot directly assign a subroutine to the “grand\_child” because this subroutine is not called within the root program, i.e. it is indirectly called by “child”. However, the returned `ReferenceManager` is a dict-like object, and you can still reach to “grand\_child” via the “child” program with the following chained dict access.

```python
main.references[("child", )].references[("grand_child", )]
```

Note that [`ScheduleBlock.parameters`](#qiskit.pulse.ScheduleBlock.parameters "qiskit.pulse.ScheduleBlock.parameters") still collects all parameters also from the subroutine once it’s assigned.

Create an empty schedule block.

**Parameters**

- **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str) *| None*) – Name of this schedule. Defaults to an autogenerated string if not provided.
- **metadata** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict) *| None*) – Arbitrary key value metadata to associate with the schedule. This gets stored as free-form data in a dict in the [`metadata`](#qiskit.pulse.ScheduleBlock.metadata "qiskit.pulse.ScheduleBlock.metadata") attribute. It will not be directly used in the schedule.
- **alignment\_context** ([*AlignmentKind*](/docs/api/qiskit/1.1/pulse#qiskit.pulse.transforms.AlignmentKind "qiskit.pulse.transforms.AlignmentKind")) – `AlignmentKind` instance that manages scheduling of instructions in this block.

**Raises**

[**TypeError**](https://docs.python.org/3/library/exceptions.html#TypeError) – if metadata is not a dict.

## Attributes

### alignment\_context

Return alignment instance that allocates block component to generate schedule.

### blocks

Get the block elements added to self.

> **Note**
>
> The sequence of elements is returned in order of addition. Because the first element is schedule first, e.g. FIFO, the returned sequence is roughly time-ordered. However, in the parallel alignment context, especially in the as-late-as-possible scheduling, or [`AlignRight`](/docs/api/qiskit/1.1/qiskit.pulse.transforms.AlignRight "qiskit.pulse.transforms.AlignRight") context, the actual timing of when the instructions are issued is unknown until the [`ScheduleBlock`](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock") is scheduled and converted into a [`Schedule`](/docs/api/qiskit/1.1/qiskit.pulse.Schedule "qiskit.pulse.Schedule").

### channels

Returns channels that this schedule block uses.

### duration

Duration of this schedule block.

### instances\_counter

Default value: `count(0)`

### instructions

Get the time-ordered instructions from self.

### metadata

The user provided metadata associated with the schedule.

User provided `dict` of metadata for the schedule. The metadata contents do not affect the semantics of the program but are used to influence the execution of the schedule. It is expected to be passed between all transforms of the schedule and that providers will associate any schedule metadata with the results it returns from the execution of that schedule.

### name

Return name of this schedule

### parameters

Return unassigned parameters with raw names.

### prefix

Default value: `'block'`

### references

Return a reference manager of the current scope.

## Methods

### append

`append(block, name=None, inplace=True)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1203-L1262)

Return a new schedule block with `block` appended to the context block. The execution time is automatically assigned when the block is converted into schedule.

**Parameters**

- **block** (*BlockComponent*) – ScheduleBlock to be appended.
- **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str) *| None*) – Name of the new `Schedule`. Defaults to name of `self`.
- **inplace** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Perform operation inplace on this schedule. Otherwise, return a new `Schedule`.

**Returns**

Schedule block with appended schedule.

**Raises**

[**PulseError**](/docs/api/qiskit/1.1/pulse#qiskit.pulse.PulseError "qiskit.pulse.PulseError") – When invalid schedule type is specified.

**Return type**

[ScheduleBlock](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock")

### assign\_parameters

`assign_parameters(value_dict, inplace=True)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1417-L1454)

Assign the parameters in this schedule according to the input.

**Parameters**

- **value\_dict** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict)*\[*[*ParameterExpression*](/docs/api/qiskit/1.1/qiskit.circuit.ParameterExpression "qiskit.circuit.ParameterExpression")  *|*[*ParameterVector*](/docs/api/qiskit/1.1/qiskit.circuit.ParameterVector "qiskit.circuit.ParameterVector")  *|*[*str*](https://docs.python.org/3/library/stdtypes.html#str)*, ParameterValueType | Sequence\[ParameterValueType]]*) – A mapping from parameters or parameter names (parameter vector
- **values** (*or parameter vector name) to either numeric*) –
- **expression** (*or another parameter*) –
- **inplace** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Set `True` to override this instance with new parameter.

**Returns**

Schedule with updated parameters.

**Raises**

[**PulseError**](/docs/api/qiskit/1.1/pulse#qiskit.pulse.PulseError "qiskit.pulse.PulseError") – When the block is nested into another block.

**Return type**

[ScheduleBlock](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock")

### assign\_references

`assign_references(subroutine_dict, inplace=True)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1456-L1534)

Assign schedules to references.

It is only capable of assigning a schedule block to immediate references which are directly referred within the current scope. Let’s see following example:

```python
from qiskit import pulse

with pulse.build() as subroutine:
    pulse.delay(10, pulse.DriveChannel(0))

with pulse.build() as sub_prog:
    pulse.reference("A")

with pulse.build() as main_prog:
    pulse.reference("B")
```

In above example, the `main_prog` can refer to the subroutine “root::B” and the reference of “B” to program “A”, i.e., “B::A”, is not defined in the root namespace. This prevents breaking the reference “root::B::A” by the assignment of “root::B”. For example, if a user could indirectly assign “root::B::A” from the root program, one can later assign another program to “root::B” that doesn’t contain “A” within it. In this situation, a reference “root::B::A” would still live in the reference manager of the root. However, the subroutine “root::B::A” would no longer be used in the actual pulse program. To assign subroutine “A” to `nested_prog` as a nested subprogram of `main_prog`, you must first assign “A” of the `sub_prog`, and then assign the `sub_prog` to the `main_prog`.

```python
sub_prog.assign_references({("A", ): nested_prog}, inplace=True)
main_prog.assign_references({("B", ): sub_prog}, inplace=True)
```

Alternatively, you can also write

```python
main_prog.assign_references({("B", ): sub_prog}, inplace=True)
main_prog.references[("B", )].assign_references({"A": nested_prog}, inplace=True)
```

Here [`references`](#qiskit.pulse.ScheduleBlock.references "qiskit.pulse.ScheduleBlock.references") returns a dict-like object, and you can mutably update the nested reference of the particular subroutine.

> **Note**
>
> Assigned programs are deep-copied to prevent an unexpected update.

**Parameters**

- **subroutine\_dict** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict)*\[*[*str*](https://docs.python.org/3/library/stdtypes.html#str)  *|*[*tuple*](https://docs.python.org/3/library/stdtypes.html#tuple)*\[*[*str*](https://docs.python.org/3/library/stdtypes.html#str)*, ...], 'ScheduleBlock']*) – A mapping from reference key to schedule block of the subroutine.
- **inplace** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Set `True` to override this instance with new subroutine.

**Returns**

Schedule block with assigned subroutine.

**Raises**

[**PulseError**](/docs/api/qiskit/1.1/pulse#qiskit.pulse.PulseError "qiskit.pulse.PulseError") – When reference key is not defined in the current scope.

**Return type**

[ScheduleBlock](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock")

### ch\_duration

`ch_duration(*channels)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1194-L1201)

Return the time of the end of the last instruction over the supplied channels.

**Parameters**

**\*channels** ([*Channel*](/docs/api/qiskit/1.1/pulse#qiskit.pulse.channels.Channel "qiskit.pulse.channels.Channel")) – Channels within `self` to include.

**Return type**

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

### draw

`draw(style=None, backend=None, time_range=None, time_unit='dt', disable_channels=None, show_snapshot=True, show_framechange=True, show_waveform_info=True, plot_barrier=True, plotter='mpl2d', axis=None, show_barrier=True)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1649-L1722)

Plot the schedule.

**Parameters**

- **style** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict)*\[*[*str*](https://docs.python.org/3/library/stdtypes.html#str)*, Any] | None*) – Stylesheet options. This can be dictionary or preset stylesheet classes. See `IQXStandard`, `IQXSimple`, and `IQXDebugging` for details of preset stylesheets.

- **backend** (*Optional\[BaseBackend]*) – Backend object to play the input pulse program. If provided, the plotter may use to make the visualization hardware aware.

- **time\_range** ([*tuple*](https://docs.python.org/3/library/stdtypes.html#tuple)*\[*[*int*](https://docs.python.org/3/library/functions.html#int)*,* [*int*](https://docs.python.org/3/library/functions.html#int)*] | None*) – Set horizontal axis limit. Tuple `(tmin, tmax)`.

- **time\_unit** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)) – The unit of specified time range either `dt` or `ns`. The unit of ns is available only when `backend` object is provided.

- **disable\_channels** ([*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*Channel*](/docs/api/qiskit/1.1/pulse#qiskit.pulse.channels.Channel "qiskit.pulse.channels.Channel")*] | None*) – A control property to show specific pulse channel. Pulse channel instances provided as a list are not shown in the output image.

- **show\_snapshot** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Show snapshot instructions.

- **show\_framechange** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Show frame change instructions. The frame change represents instructions that modulate phase or frequency of pulse channels.

- **show\_waveform\_info** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Show additional information about waveforms such as their name.

- **plot\_barrier** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Show barrier lines.

- **plotter** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)) –

  Name of plotter API to generate an output image. One of following APIs should be specified:

  ```python
  mpl2d: Matplotlib API for 2D image generation.
      Matplotlib API to generate 2D image. Charts are placed along y axis with
      vertical offset. This API takes matplotlib.axes.Axes as ``axis`` input.
  ```

  `axis` and `style` kwargs may depend on the plotter.

- **axis** (*Any | None*) – Arbitrary object passed to the plotter. If this object is provided, the plotters use a given `axis` instead of internally initializing a figure object. This object format depends on the plotter. See plotter argument for details.

- **show\_barrier** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – DEPRECATED. Show barrier lines.

**Returns**

Visualization output data. The returned data type depends on the `plotter`. If matplotlib family is specified, this will be a `matplotlib.pyplot.Figure` data.

### exclude

`exclude(*filter_funcs, channels=None, instruction_types=None, check_subroutine=True)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1303-L1339)

Return a new `ScheduleBlock` with only the instructions from this `ScheduleBlock` *failing* at least one of the provided filters. This method is the complement of [`filter()`](#qiskit.pulse.ScheduleBlock.filter "qiskit.pulse.ScheduleBlock.filter"), so that:

```python
self.filter(args) + self.exclude(args) == self in terms of instructions included.
```

> **Warning**
>
> Because `ScheduleBlock` is not aware of the execution time of the context instructions, excluding some instructions may change the execution time of the remaining instructions.

**Parameters**

- **filter\_funcs** (*Callable\[...,* [*bool*](https://docs.python.org/3/library/functions.html#bool)*]*) – A list of Callables which take a `Instruction` and return a bool.
- **channels** (*Iterable\[*[*Channel*](/docs/api/qiskit/1.1/pulse#qiskit.pulse.channels.Channel "qiskit.pulse.channels.Channel")*] | None*) – For example, `[DriveChannel(0), AcquireChannel(0)]`.
- **instruction\_types** (*Iterable\[*[*abc.ABCMeta*](https://docs.python.org/3/library/abc.html#abc.ABCMeta)*] |* [*abc.ABCMeta*](https://docs.python.org/3/library/abc.html#abc.ABCMeta)) – For example, `[PulseInstruction, AcquireInstruction]`.
- **check\_subroutine** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Set True to individually filter instructions inside of a subroutine defined by the `Call` instruction.

**Returns**

`ScheduleBlock` consisting of instructions that do not match with at least one of filtering conditions.

### filter

`filter(*filter_funcs, channels=None, instruction_types=None, check_subroutine=True)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1264-L1301)

Return a new `ScheduleBlock` with only the instructions from this `ScheduleBlock` which pass though the provided filters; i.e. an instruction will be retained if every function in `filter_funcs` returns `True`, the instruction occurs on a channel type contained in `channels`, and the instruction type is contained in `instruction_types`.

> **Warning**
>
> Because `ScheduleBlock` is not aware of the execution time of the context instructions, filtering out some instructions may change the execution time of the remaining instructions.

If no arguments are provided, `self` is returned.

**Parameters**

- **filter\_funcs** (*Callable\[...,* [*bool*](https://docs.python.org/3/library/functions.html#bool)*]*) – A list of Callables which take a `Instruction` and return a bool.
- **channels** (*Iterable\[*[*Channel*](/docs/api/qiskit/1.1/pulse#qiskit.pulse.channels.Channel "qiskit.pulse.channels.Channel")*] | None*) – For example, `[DriveChannel(0), AcquireChannel(0)]`.
- **instruction\_types** (*Iterable\[*[*abc.ABCMeta*](https://docs.python.org/3/library/abc.html#abc.ABCMeta)*] |* [*abc.ABCMeta*](https://docs.python.org/3/library/abc.html#abc.ABCMeta)) – For example, `[PulseInstruction, AcquireInstruction]`.
- **check\_subroutine** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Set True to individually filter instructions inside a subroutine defined by the `Call` instruction.

**Returns**

`ScheduleBlock` consisting of instructions that matches with filtering condition.

### get\_parameters

`get_parameters(parameter_name)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1536-L1568)

Get parameter object bound to this schedule by string name.

Note that we can define different parameter objects with the same name, because these different objects are identified by their unique uuid. For example,

```python
from qiskit import pulse, circuit

amp1 = circuit.Parameter("amp")
amp2 = circuit.Parameter("amp")

with pulse.build() as sub_prog:
    pulse.play(pulse.Constant(100, amp1), pulse.DriveChannel(0))

with pulse.build() as main_prog:
    pulse.call(sub_prog, name="sub")
    pulse.play(pulse.Constant(100, amp2), pulse.DriveChannel(0))

main_prog.get_parameters("amp")
```

This returns a list of two parameters `amp1` and `amp2`.

**Parameters**

**parameter\_name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)) – Name of parameter.

**Returns**

Parameter objects that have corresponding name.

**Return type**

[list](https://docs.python.org/3/library/stdtypes.html#list)\[[qiskit.circuit.parameter.Parameter](/docs/api/qiskit/1.1/qiskit.circuit.Parameter "qiskit.circuit.parameter.Parameter")]

### initialize\_from

*classmethod* `initialize_from(other_program, name=None)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1044-L1076)

Create new schedule object with metadata of another schedule object.

**Parameters**

- **other\_program** (*Any*) – Qiskit program that provides metadata to new object.
- **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str) *| None*) – Name of new schedule. Name of `block` is used by default.

**Returns**

New block object with name and metadata.

**Raises**

[**PulseError**](/docs/api/qiskit/1.1/pulse#qiskit.pulse.PulseError "qiskit.pulse.PulseError") – When `other_program` does not provide necessary information.

**Return type**

[ScheduleBlock](#qiskit.pulse.ScheduleBlock "qiskit.pulse.ScheduleBlock")

### is\_parameterized

`is_parameterized()`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1409-L1411)

Return True iff the instruction is parameterized.

**Return type**

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

### is\_referenced

`is_referenced()`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1413-L1415)

Return True iff the current schedule block contains reference to subroutine.

**Return type**

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

### is\_schedulable

`is_schedulable()`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1108-L1126)

Return `True` if all durations are assigned.

**Return type**

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

### replace

`replace(old, new, inplace=True)`

[GitHub](https://github.com/Qiskit/qiskit/tree/stable/1.1/qiskit/pulse/schedule.py#L1341-L1407)

Return a `ScheduleBlock` with the `old` component replaced with a `new` component.

**Parameters**

- **old** ([*ScheduleBlock*](#qiskit.pulse.ScheduleBlock "qiskit.pulse.schedule.ScheduleBlock")  *|*[*Instruction*](/docs/api/qiskit/1.1/pulse#qiskit.pulse.instructions.Instruction "qiskit.pulse.instructions.instruction.Instruction")) – Schedule block component to replace.
- **new** ([*ScheduleBlock*](#qiskit.pulse.ScheduleBlock "qiskit.pulse.schedule.ScheduleBlock")  *|*[*Instruction*](/docs/api/qiskit/1.1/pulse#qiskit.pulse.instructions.Instruction "qiskit.pulse.instructions.instruction.Instruction")) – Schedule block component to replace with.
- **inplace** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Replace instruction by mutably modifying this `ScheduleBlock`.

**Returns**

The modified schedule block with `old` replaced by `new`.

**Return type**

[*ScheduleBlock*](#qiskit.pulse.ScheduleBlock "qiskit.pulse.schedule.ScheduleBlock")