ThresholdSpecification¶

class lsst.verify.ThresholdSpecification(name, threshold, operator_str, **kwargs)¶

Bases: lsst.verify.Specification

A threshold-type specification, associated with a Metric, that defines a binary comparison against a measurement.

Parameters:

name : str: Name of the specification for a metric. LPM-17, for example, uses 'design', 'minimum' and 'stretch' terminology.
quantity : astropy.units.Quantity: The specification threshold level.
operator_str : str: The threshold’s binary comparison operator. The operator is oriented so that measurement {{ operator }} threshold quantity is the specification test. Can be one of: '<', '<=', '>', '>=', '==', or '!='.
metadata_query : dict, optional: Dictionary of key-value terms that the measurement’s metadata must have for this specification to apply.
tags : sequence of str, optional: Sequence of tags that group this specification with others.
kwargs : dict: Keyword arguments passed directly to the lsst.validate.base.Specification constructor.

Raises:

TypeError: If name is not compartible with Name, or threshold is not a Quantity, or if the operator_str cannot be converted into a Python binary comparison operator.

Attributes Summary

`datum`	Representation of this `ThresholdSpecification`’s threshold as a `Datum`.
`json`	`dict` that can be serialized as semantic JSON, compatible with the SQUASH metric service.
`metric_name`	Name of the metric this specification corresponds to (`lsst.verify.Name`).
`name`	Specification name (`lsst.verify.Name`).
`operator`	Binary comparision operator that tests success of a measurement fulfilling a specification of this metric.
`operator_str`	Threshold comparision operator (‘str’).
`tags`	Tag labels (`set` of `str`).
`threshold`	The specification threshold level (`astropy.units.Quantity`).
`type`	Specification type (`str`).

Methods Summary

`check`(measurement)	Check if a measurement passes this specification.
`convert_operator_str`(op_str)	Convert a string representing a binary comparison operator to the operator function itself.
`deserialize`([name, threshold, metric, package])	Deserialize from keys in a specification YAML document or a JSON serialization into a `ThresholdSpecification` instance.
`jsonify_dict`(d)	Recursively build JSON-renderable objects on all values in a dict.
`query_metadata`(metadata[, arg_driven])	Query a Job’s metadata to determine if this specification applies.
`write_json`(filepath)	Write JSON to a file.

Attributes Documentation

datum¶: Representation of this ThresholdSpecification’s threshold as a Datum.

json¶: dict that can be serialized as semantic JSON, compatible with the SQUASH metric service.

metric_name¶: Name of the metric this specification corresponds to (lsst.verify.Name).

name¶: Specification name (lsst.verify.Name).

operator¶

Binary comparision operator that tests success of a measurement fulfilling a specification of this metric.

Measured value is on left side of comparison and specification level is on right side.

operator_str¶

Threshold comparision operator (‘str’).

A measurement passes the specification if:

measurement {{ operator }} threshold == True

The operator string is a standard Python binary comparison token, such as: '<', '>', '<=', '>=', '==' or '!='.

tags¶: Tag labels (set of str).

threshold = None¶: The specification threshold level (astropy.units.Quantity).

type¶: Specification type (str).

Methods Documentation

check(measurement)¶

Check if a measurement passes this specification.

Parameters:	measurement : `astropy.units.Quantity` The measurement value. The measurement `Quantity` must have units compatible with `threshold`.
Returns:	passed : `bool` `True` if the measurement meets the specification, `False` otherwise.
Raises:	astropy.units.UnitError Raised if the measurement cannot be compared to the threshold. For example, if the measurement is not an `astropy.units.Quantity` or if the units are not compatible.

static convert_operator_str(op_str)¶

Convert a string representing a binary comparison operator to the operator function itself.

Operators are oriented so that the measurement is on the left-hand side, and specification threshold on the right hand side.

The following operators are permitted:

`op_str`	Function
`>=`	`operator.ge`
`>`	`operator.gt`
`<`	`operator.lt`
`<=`	`operator.le`
`==`	`operator.eq`
`!=`	`operator.ne`

Parameters:	op_str : `str` A string representing a binary operator.
Returns:	op_func : obj An operator function from the `operator` standard library module.
Raises:	ValueError Raised if `op_str` is not a supported binary comparison operator.

classmethod deserialize(name=None, threshold=None, metric=None, package=None, **kwargs)¶

Deserialize from keys in a specification YAML document or a JSON serialization into a ThresholdSpecification instance.

Parameters:

name : str or lsst.validate.base.Name

Specification name, either as a string or Name.

threshold : dict

A dict with fields:

'value': threshold value (float or int).
'unit': threshold unit, as an astropy.units.Unit- compatible str.
'operator': a binary comparison operator, described in the class parameters documentation (str).

metric : str or lsst.validate.base.Name, optional

Name of the fully-qualified name of the metric the specification corresponds to. This parameter is optional if name is already fully-qualified.

package : str or lsst.validate.base.Name, optional

Name of the package the specification corresponds to. This parameter is optional if name or metric are already fully-qualified.

kwargs : dict

Keyword arguments passed directly to the lsst.validate.base.Specification constructor.

Returns:

specification : ThresholdSpecification: A specification instance.

static jsonify_dict(d)¶

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

Parameters:	d : `dict` Dictionary to convert into a JSON-serializable object. Values are recursively JSON-ified.
Returns:	json_dict : `dict` 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,
    })

query_metadata(metadata, arg_driven=False)¶

Query a Job’s metadata to determine if this specification applies.

Parameters:

metadata : lsst.verify.Metadata or dict-type

Metadata mapping. Typically this is the lsst.verify.Job.meta attribute.

arg_driven : bool, optional

If False (default), metadata matches the MetadataQuery if metadata has all the terms defined in MetadataQuery, and those terms match. If metadata has more terms than MetadataQuery, it can still match. This behavior is appropriate for finding if a specification applies to a Job given metadata.

If True, the orientation of the matching is reversed. Now metadata matches the MetadataQuery if MetadataQuery has all the terms defined in metadata and those terms match. If MetadataQuery has more terms than metadata, it can still match. This behavior is appropriate for discovering specifications.

Returns:

matched : bool: True if this specification matches, False otherwise.

Navigation

ThresholdSpecification¶