import numpy as np
__all__ = ["RULE_FUNCTIONS", "AttributeBlender", "make_blender"]
def _multi(vals):
"""
Return either the common value from a list of identical values or 'MULTIPLE'.
Parameters
----------
vals : list
List of values to check.
Returns
-------
value : str or None
The common value from the list of identical values or 'MULTIPLE'.
"""
uniq_vals = list(set(vals))
num_vals = len(uniq_vals)
if num_vals == 0:
return None
if num_vals == 1:
return uniq_vals[0]
if num_vals > 1:
return "MULTIPLE"
def _wheeltol(vals):
"""
Return 'outside calibration tolerance' if any value in list matches that string.
Parameters
----------
vals : list
List of values to check.
Returns
-------
value : str or None
'outside calibration tolerance' if any value in list matches that string,
otherwise 'within commanded tolerance'. Returns None if the input list is empty.
"""
if not vals:
return None
if any(val == "outside calibration tolerance" for val in vals):
return "outside calibration tolerance"
return "within commanded tolerance"
RULE_FUNCTIONS = {
"multi": _multi,
"mean": np.mean,
"sum": np.sum,
"max": np.max,
"min": np.min,
# retained date/time names for backwards compatibility
# as these all assume ISO8601 format the lexical and
# chronological sorting match
"mintime": min,
"maxtime": max,
"mindate": min,
"maxdate": max,
"mindatetime": min,
"maxdatetime": max,
"wheeltol": _wheeltol,
}
"""
Mapping of rule names to functions.
Used for :func:`make_blender`.
The following rules are considered deprecated
and should not be used for new schemas:
- mintime
- maxtime
- mindate
- maxdate
- mindatetime
- maxdatetime
"""
[docs]
class AttributeBlender:
"""
Single attribute metadata blender.
Parameters
----------
blend_function : callable
Function to blend accumulated metadata values
"""
def __init__(self, blend_function):
self.blend_function = blend_function
self.values = []
[docs]
def accumulate(self, value):
"""
Add a metadata value for blending.
Parameters
----------
value : any
Value for this metadata attribute to use when blending.
"""
self.values.append(value)
[docs]
def finalize(self):
"""
Blend the accumulated metadata values.
Returns
-------
value
The blended result.
"""
if not self.values:
return None
return self.blend_function(self.values)
[docs]
def make_blender(rule):
"""
Make an `AttributeBlender` instance using the provided rule.
Parameters
----------
rule : str
Name of the blending rule. Must be in `RULE_FUNCTIONS`.
Returns
-------
attr_blender : `AttributeBlender`
Blender instance using the provided rule.
"""
return AttributeBlender(RULE_FUNCTIONS[rule])