qiskit/transpiler/layout.py
def from_tuplelist(tuple_list):
        """
        Populates a Layout from a list containing virtual
        qubits---(QuantumRegister, int) tuples---, or None.

        Args:
            tuple_list (list):
                e.g.: [qr[0], None, qr[2], qr[3]]
        Returns:
            Layout: the corresponding Layout object
        Raises:
            LayoutError: If the elements are not (Register, integer) or None
        """
        out = Layout()
        for physical, virtual in enumerate(tuple_list):
            if virtual is None:
                continue
            elif Layout.is_virtual(virtual):
                if virtual in out._v2p:
                    raise LayoutError('Duplicate values not permitted; Layout is bijective.')
                out[virtual] = physical
            else:
                raise LayoutError("The list should contain elements of the form"
                                  " (Register, integer) or None")
        return out
def from_tuplelist(tuple_list):
        """
        Populates a Layout from a list containing virtual
        qubits---(QuantumRegister, int) tuples---, or None.

        Args:
            tuple_list (list):
                e.g.: [qr[0], None, qr[2], qr[3]]
        Returns:
            Layout: the corresponding Layout object
        Raises:
            LayoutError: If the elements are not (Register, integer) or None
        """
        out = Layout()
        for physical, virtual in enumerate(tuple_list):
            if virtual is None:
                continue
            elif Layout.is_virtual(virtual):
                if virtual in out._v2p:
                    raise LayoutError('Duplicate values not permitted; Layout is bijective.')
                out[virtual] = physical
            else:
                raise LayoutError("The list should contain elements of the form"
                                  " (Register, integer) or None")
        return out
Populates a Layout from a list containing virtual
        qubits---(QuantumRegister, int) tuples---, or None.

        Args:
            tuple_list (list):
                e.g.: [qr[0], None, qr[2], qr[3]]
        Returns:
            Layout: the corresponding Layout object
        Raises:
            LayoutError: If the elements are not (Register, integer) or None