Note
This is the documentation for the current state of the development branch of Qiskit Experiments. The documentation or APIs here can change prior to being released.
ExperimentEncoder¶
- class ExperimentEncoder(*, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, sort_keys=False, indent=None, separators=None, default=None)[source]¶
JSON Encoder for Qiskit Experiments.
This class extends the default Python JSONEncoder by including built-in support for
complex numbers, inf and NaN floats, sets, and dataclasses.
NumPy ndarrays and SciPy sparse matrices.
Qiskit
QuantumCircuit
.Any class that implements a
__json_encode__
method or asettings
property.
Generic classes can be serialized by this encoder. This is done by attempting the following methods in order:
The object has a
__json_encode__
method. This should have signaturedef __json_encode__(self) -> Any: # return a JSON serializable object value
The value returned by
__json_encode__
must be an object that can be serialized by the JSON encoder (for example adict
containing other JSON serializable objects).To deserialize this object using the
ExperimentDecoder
the class must also provide a__json_decode__
class method that can convert the value returned by__json_encode__
back to the object. This method should have signature@classmethod def __json_decode__(cls, value: Any) -> cls: # recover the object from the `value` returned by __json_encode__
The object has a
settings
property. This should have signature@property def settings(self) -> Dict[str, Any]: # Return settings value for reconstructing the instance
Deserialization of objects from the
value
dictionary returned bysettings
is done by calling the class __init__ methodcls(**settings)
.In all other cases only the object class is saved. Deserialization will attempt to recover the object from default initialization of its class as
cls()
.
Note
Serialization of custom classes works for user-defined classes in Python scripts, notebooks, or third party modules. Note however that these will only be able to be de-serialized if that class can be imported form the same scope at the time the
ExperimentDecoder
is invoked.Constructor for JSONEncoder, with sensible defaults.
If skipkeys is false, then it is a TypeError to attempt encoding of keys that are not str, int, float or None. If skipkeys is True, such items are simply skipped.
If ensure_ascii is true, the output is guaranteed to be str objects with all incoming non-ASCII characters escaped. If ensure_ascii is false, the output can contain non-ASCII characters.
If check_circular is true, then lists, dicts, and custom encoded objects will be checked for circular references during encoding to prevent an infinite recursion (which would cause an RecursionError). Otherwise, no such check takes place.
If allow_nan is true, then NaN, Infinity, and -Infinity will be encoded as such. This behavior is not JSON specification compliant, but is consistent with most JavaScript based encoders and decoders. Otherwise, it will be a ValueError to encode such floats.
If sort_keys is true, then the output of dictionaries will be sorted by key; this is useful for regression tests to ensure that JSON serializations can be compared on a day-to-day basis.
If indent is a non-negative integer, then JSON array elements and object members will be pretty-printed with that indent level. An indent level of 0 will only insert newlines. None is the most compact representation.
If specified, separators should be an (item_separator, key_separator) tuple. The default is (’, ‘, ‘: ‘) if indent is
None
and (‘,’, ‘: ‘) otherwise. To get the most compact JSON representation, you should specify (‘,’, ‘:’) to eliminate whitespace.If specified, default is a function that gets called for objects that can’t otherwise be serialized. It should return a JSON encodable version of the object or raise a
TypeError
.Attributes
- item_separator = ', '¶
- key_separator = ': '¶
Methods
- default(obj)[source]¶
Implement this method in a subclass such that it returns a serializable object for
o
, or calls the base implementation (to raise aTypeError
).For example, to support arbitrary iterators, you could implement default like this:
def default(self, o): try: iterable = iter(o) except TypeError: pass else: return list(iterable) # Let the base class default method raise the TypeError return super().default(o)
- Return type:
Any
- encode(o)¶
Return a JSON string representation of a Python data structure.
>>> from json.encoder import JSONEncoder >>> JSONEncoder().encode({"foo": ["bar", "baz"]}) '{"foo": ["bar", "baz"]}'
- iterencode(o, _one_shot=False)¶
Encode the given object and yield each string representation as available.
For example:
for chunk in JSONEncoder().iterencode(bigobject): mysocket.write(chunk)