qiskit/releasenotes/notes/0.25/add-method-for-mapping-qubit-clbit-to-positional-index-6cd43a42f56eb549.yaml

---
features:
  - |
    A new method, :meth:`~qiskit.dagcircuit.dag.find_bit`, has
    been added to the :class:`~qiskit.dagcircuit.DagCircuit` class.
    This is a method to get mapping of Qubit and Clbit to positional index. 
    The method takes a Bit as input, checks whether it's a Qubit or a Clbit, 
    and then returns the corresponding BitLocations from the respective index 
    dictionary (_qubit_indices or _clbit_indices).
    The BitLocations is a namedtuple which includes the positional index of the 
    bit in the circuit and a list of registers containing the bit. If the bit 
    cannot be found or is of an unknown type, it raises a DAGCircuitError.