Datum¶

class lsst.verify.Datum(quantity=None, unit=None, label=None, description=None)¶

Bases: QuantityAttributeMixin, JsonSerializationMixin

A value annotated with units, a plot label and description.

Datum supports natively support Astropy Quantity and units. In addition, a Datum can also wrap strings, booleans and integers. A Datums’s value can also be None.

Parameters:

quantityastropy.units.Quantity, int, float or iterable.: Value of the Datum.
unitstr: Units of quantity as a str if quantity is not supplied as an astropy.units.Quantity. See http://docs.astropy.org/en/stable/units/. Units are not used by str, bool, int or None types.
labelstr, optional: Label suitable for plot axes (without units).
descriptionstr, optional: Extended description of the Datum.

Attributes Summary

`description`	Extended description.
`json`	Datum as a `dict` compatible with overall `Job` JSON schema.
`label`	Label for plotting (without units).
`latex_unit`	Units as a LaTeX string, wrapped in `$`.
`quantity`	Value of the datum (`astropy.units.Quantity`, `str`, `bool`, `None`).
`unit`	Read-only `astropy.units.Unit` of the `quantity`.
`unit_str`	Read-only `astropy.units.Unit`-compatible `str` indicating units of `quantity`.

Methods Summary

`deserialize`([label, description, value, unit])	Deserialize fields from a Datum JSON object into a `Datum` instance.
`jsonify_dict`(d)	Recursively build JSON-renderable objects on all values in a dict.
`write_json`(filepath)	Write JSON to a file.

Attributes Documentation

description¶: Extended description.

json¶: Datum as a dict compatible with overall Job JSON schema.

label¶: Label for plotting (without units).

latex_unit¶: Units as a LaTeX string, wrapped in $.

quantity¶: Value of the datum (astropy.units.Quantity, str, bool, None).

unit¶

Read-only astropy.units.Unit of the quantity.

If the quantity is a str or bool, the unit is None.

unit_str¶: Read-only astropy.units.Unit-compatible str indicating units of quantity.

Methods Documentation

classmethod deserialize(label=None, description=None, value=None, unit=None)¶

Deserialize fields from a Datum JSON object into a Datum instance.

Parameters:

valuefloat, int, bool, str, or list: Values, which may be scalars or lists of scalars.
unitstr or None: An astropy.units-compatible string with units of value, or None if the value does not have physical units.
labelstr, optional: Label suitable for plot axes (without units).
descriptionstr, optional: Extended description of the Datum.

Returns:

datumDatum: Datum instantiated from provided JSON fields.

Examples

With this class method, a Datum may be round-tripped from its JSON serialized form.

>>> datum = Datum(50. * u.mmag, label='sigma',
...               description="Photometric uncertainty.")
>>> print(datum)
sigma = 50.0 mmag
Photometric uncertainty.
>>> json_data = datum.json
>>> new_datum = datum.deserialize(**json_data)
>>> print(new_datum)
sigma = 50.0 mmag
Photometric uncertainty.

static jsonify_dict(d)¶

Recursively build JSON-renderable objects on all values in a dict.

Parameters:

ddict: Dictionary to convert into a JSON-serializable object. Values are recursively JSON-ified.

Returns:

json_dictdict: Dictionary that can be serialized to JSON.

Examples

Subclasses can use this method to prepare output in their json-method implementation. For example:

def json(self):
    return JsonSerializationMixin.jsonify_dict({
        'value': self.value,
    })

write_json(filepath)¶

Write JSON to a file.

Parameters:

filepathstr: Destination file name for JSON output.

Navigation

Datum¶