--- title: OperatorTrait (latest version) description: API reference for qiskit_fermions.operators.OperatorTrait in the latest version of qiskit-fermions source: https://quantum.cloud.ibm.com/docs/en/api/qiskit-fermions/operators-operator-trait --- # OperatorTrait *class* `OperatorTrait(*args, **kwargs)` Bases: [`Protocol`](https://docs.python.org/3/library/typing.html#typing.Protocol) A protocol indicating all methods implemented by operator classes. ## Attributes ### groups Returns the groups indices. ## Methods ### adjoint `adjoint()` Returns the adjoint of this operator. **Return type** [*Self*](https://docs.python.org/3/library/typing.html#typing.Self) ### equiv `equiv(other, atol)` Checks this operator with another for equivalence up to the specified absolute tolerance. **Parameters** - **other** ([*Self*](https://docs.python.org/3/library/typing.html#typing.Self)) - **atol** ([*float*](https://docs.python.org/3/library/functions.html#float)) **Return type** [bool](https://docs.python.org/3/library/functions.html#bool) ### from\_terms *classmethod* `from_terms(terms)` Constructs a new operator from an iterator (see also [`iter_terms()`](#qiskit_fermions.operators.OperatorTrait.iter_terms "qiskit_fermions.operators.OperatorTrait.iter_terms")). **Parameters** **terms** ([*Iterable*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Iterable)) **Return type** [*Self*](https://docs.python.org/3/library/typing.html#typing.Self) ### from\_terms\_with\_groups *classmethod* `from_terms_with_groups(terms)` Constructs a new operator from an iterator (see also [`iter_terms_with_groups()`](#qiskit_fermions.operators.OperatorTrait.iter_terms_with_groups "qiskit_fermions.operators.OperatorTrait.iter_terms_with_groups")). **Parameters** **terms** ([*Iterable*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Iterable)) **Return type** [*Self*](https://docs.python.org/3/library/typing.html#typing.Self) ### get\_coeffs `get_coeffs()` Returns the term coefficients. **Return type** [list](https://docs.python.org/3/library/stdtypes.html#list)\[[complex](https://docs.python.org/3/library/functions.html#complex)] ### get\_support `get_support()` Returns the set of mode indices which this operator acts upon. **Return type** [frozenset](https://docs.python.org/3/library/stdtypes.html#frozenset)\[[int](https://docs.python.org/3/library/functions.html#int)] ### group\_weights `group_weights()` Returns the mean absolute coefficient magnitude of each group. This is equivalent to (but cheaper than) reducing [`get_coeffs()`](#qiskit_fermions.operators.OperatorTrait.get_coeffs "qiskit_fermions.operators.OperatorTrait.get_coeffs") and [`groups`](#qiskit_fermions.operators.OperatorTrait.groups "qiskit_fermions.operators.OperatorTrait.groups") down to one value per group in NumPy, because it does not copy one value per *ungrouped* term out of the operator just to aggregate it away again. **Return type** [list](https://docs.python.org/3/library/stdtypes.html#list)\[[float](https://docs.python.org/3/library/functions.html#float)] | None ### has\_groups `has_groups()` Returns whether this operator tracks group indices. This is equivalent to (but cheaper than) checking `op.groups is not None`, because it does not copy the group indices out of the operator in order to inspect them. **Return type** [bool](https://docs.python.org/3/library/functions.html#bool) ### ichop `ichop(atol)` Trims coefficients below the absolute tolerance from this operator. **Parameters** **atol** ([*float*](https://docs.python.org/3/library/functions.html#float)) ### iter\_terms `iter_terms()` Iterates over the terms of this operator. **Return type** [*Iterator*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Iterator) ### iter\_terms\_with\_groups `iter_terms_with_groups()` Iterates over the terms of this operator with their group indices. **Return type** [*Iterator*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Iterator) ### normal\_ordered `normal_ordered(*args, **kwargs)` Returns the normal-ordered form of this operator. > **Note** > > A specific implementation of this method may take additional arguments. **Return type** [*Self*](https://docs.python.org/3/library/typing.html#typing.Self) ### num\_groups `num_groups()` Returns the number of groups. **Return type** [int](https://docs.python.org/3/library/functions.html#int) | None ### one *classmethod* `one()` Constructs the multiplicative identity operator. **Return type** [*Self*](https://docs.python.org/3/library/typing.html#typing.Self) ### relabel\_modes `relabel_modes(permutation)` Relabels the modes of the operator. **Parameters** **permutation** ([*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*int*](https://docs.python.org/3/library/functions.html#int)*]*) **Return type** [*Self*](https://docs.python.org/3/library/typing.html#typing.Self) ### simplify `simplify(atol)` Simplifies the terms of this operator, discarding those below the absolute tolerance. **Parameters** **atol** ([*float*](https://docs.python.org/3/library/functions.html#float)) **Return type** [*Self*](https://docs.python.org/3/library/typing.html#typing.Self) ### split\_out\_groups `split_out_groups(group_indices=None)` Splits this operator into an optional list of new operators based on its [`groups`](#qiskit_fermions.operators.OperatorTrait.groups "qiskit_fermions.operators.OperatorTrait.groups"). > **Note** > > If `group_indices` is omitted, every group is built, in index order. Otherwise, only the requested indices are built, in the given order. **Parameters** **group\_indices** ([*Sequence*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Sequence)*\[*[*int*](https://docs.python.org/3/library/functions.html#int)*] | None*) **Return type** [list](https://docs.python.org/3/library/stdtypes.html#list)\[[*Self*](https://docs.python.org/3/library/typing.html#typing.Self)] ### zero *classmethod* `zero()` Constructs the additive identity operator. **Return type** [*Self*](https://docs.python.org/3/library/typing.html#typing.Self)