InstructionDurations

class qiskit.transpiler.InstructionDurations(instruction_durations=None, dt=None)

Bases: object

Helper class to provide durations of instructions for scheduling.

It stores durations (gate lengths) and dt to be used at the scheduling stage of transpiling. It can be constructed from backend or instruction_durations, which is an argument of transpile(). The duration of an instruction depends on the instruction (given by name), the qubits, and optionally the parameters of the instruction. Note that these fields are used as keys in dictionaries that are used to retrieve the instruction durations. Therefore, users must use the exact same parameter value to retrieve an instruction duration as the value with which it was added.

Methods

classmethod from_backend(backend)

Construct an InstructionDurations object from the backend.

Parameters:

backend (Backend) – backend from which durations (gate lengths) and dt are extracted.

Returns:

The InstructionDurations constructed from backend.

Return type:

InstructionDurations

Raises:

TranspilerError – If dt and dtm is different in the backend.

get(inst, qubits, unit='dt', parameters=None)

Get the duration of the instruction with the name, qubits, and parameters.

Some instructions may have a parameter dependent duration.

Parameters:

• inst (str | qiskit.circuit.Instruction) – An instruction or its name to be queried.

• qubits (int | list[int]) – Qubit indices that the instruction acts on.

• unit (str) – The unit of duration to be returned. It must be ‘s’ or ‘dt’.

• parameters (list[float] | None) – The value of the parameters of the desired instruction.

Returns:

The duration of the instruction on the qubits.

Return type:

float|int

Raises:

TranspilerError – No duration is defined for the instruction.

units_used()

Get the set of all units used in this instruction durations.

Returns:

Set of units used in this instruction durations.

Return type:

set[str]

update(inst_durations, dt=None)

Update self with inst_durations (inst_durations overwrite self).

Parameters:

• inst_durations ('InstructionDurationsType' | None) – Instruction durations to be merged into self (overwriting self).

• dt (float) – Sampling duration in seconds of the target backend.

Returns:

The updated InstructionDurations.

Return type:

InstructionDurations

Raises:

TranspilerError – If the format of instruction_durations is invalid.