--- /dev/null
+# Copyright (c) 2019 Cisco and/or its affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Module holding BitCountingGroup class."""
+
+import copy
+
+from .AvgStdevStats import AvgStdevStats
+from .BitCountingStats import BitCountingStats
+
+
+class BitCountingGroup:
+ # TODO: Inherit from collections.abc.Sequence in Python 3.
+ """Group of runs which tracks bit count in an efficient manner.
+
+ This class contains methods that mutate the internal state,
+ use copy() method to save the previous state.
+
+ The Sequence-like access is related to the list of runs,
+ for example group[0] returns the first run in the list.
+ Writable list-like methods are not implemented.
+
+ As the group bit count depends on previous average
+ and overall maximal value, those values are assumed
+ to be known beforehand (and immutable).
+
+ As the caller is allowed to divide runs into groups in any way,
+ a method to add a single run in an efficient manner is provided.
+ """
+
+ def __init__(self, run_list=None, stats=None, bits=None,
+ max_value=None, prev_avg=None, comment="unknown"):
+ """Set the internal state and partially the stats.
+
+ A "group" stands for an Iterable of runs, where "run" is either
+ a float value, or a stats-like object (only size, avg and stdev
+ are accessed). Run is a hypothetical abstract class,
+ defining it in Python 2 is too much hassle.
+
+ Only a copy of the run list argument value is stored in the instance,
+ so it is not a problem if the value object is mutated afterwards.
+
+ It is not verified whether the user provided values are valid,
+ e.g. whether the stats and bits values reflect the runs.
+
+ :param run_list: List of run to compose into this group. Default: empty.
+ :param stats: Stats object used for computing bits.
+ :param bits: Cached value of information content.
+ :param max_value: Maximal sample value to be used for computing.
+ :param prev_avg: Average of the previous group, affects bits.
+ :param comment: Any string giving more info, e.g. "regression".
+ :type run_list: Iterable[Run]
+ :type stats: Optional[AvgStdevStats]
+ :type bits: Optional[float]
+ :type max_value: float
+ :type prev_avg: Optional[float]
+ :type comment: str
+ """
+ self.run_list = copy.deepcopy(run_list) if run_list else list()
+ self.stats = stats
+ self.cached_bits = bits
+ self.max_value = max_value
+ self.prev_avg = prev_avg
+ self.comment = comment
+ if self.stats is None:
+ self.stats = AvgStdevStats.for_runs(self.run_list)
+
+ def __str__(self):
+ """Return string with human readable description of the group.
+
+ :returns: Readable description.
+ :rtype: str
+ """
+ return f"stats={self.stats} bits={self.cached_bits}"
+
+ def __repr__(self):
+ """Return string executable as Python constructor call.
+
+ :returns: Executable constructor call.
+ :rtype: str
+ """
+ return (
+ f"BitCountingGroup(run_list={self.run_list!r},stats={self.stats!r}"
+ f",bits={self.cached_bits!r},max_value={self.max_value!r}"
+ f",prev_avg={self.prev_avg!r},comment={self.comment!r})"
+ )
+
+ def __getitem__(self, index):
+ """Return the run at the index.
+
+ :param index: Index of the run to return.
+ :type index: int
+ :returns: The run at the index.
+ :rtype: Run
+ """
+ return self.run_list[index]
+
+ def __len__(self):
+ """Return the number of runs in the group.
+
+ :returns: The Length of run_list.
+ :rtype: int
+ """
+ return len(self.run_list)
+
+ def copy(self):
+ """Return a new instance with copied internal state.
+
+ :returns: The copied instance.
+ :rtype: BitCountingGroup
+ """
+ stats = AvgStdevStats.for_runs([self.stats])
+ return self.__class__(
+ run_list=self.run_list, stats=stats, bits=self.cached_bits,
+ max_value=self.max_value, prev_avg=self.prev_avg,
+ comment=self.comment)
+
+ @property
+ def bits(self):
+ """Return overall bit content of the group list.
+
+ If not cached, compute from stats and cache.
+
+ :returns: The overall information content in bits.
+ :rtype: float
+ """
+ if self.cached_bits is None:
+ self.cached_bits = BitCountingStats.for_runs(
+ [self.stats], self.max_value, self.prev_avg).bits
+ return self.cached_bits
+
+ def append(self, run):
+ """Mutate to add the new run, return self.
+
+ Stats are updated, but old bits value is deleted from cache.
+
+ :param run: The run value to add to the group.
+ :type value: Run
+ :returns: The updated self.
+ :rtype: BitCountingGroup
+ """
+ self.run_list.append(run)
+ self.stats = AvgStdevStats.for_runs([self.stats, run])
+ self.cached_bits = None
+ return self
+
+ def extend(self, runs):
+ """Mutate to add the new runs, return self.
+
+ This is saves small amount of computation
+ compared to adding runs one by one in a loop.
+
+ Stats are updated, but old bits value is deleted from cache.
+
+ :param runs: The runs to add to the group.
+ :type value: Iterable[Run]
+ :returns: The updated self.
+ :rtype: BitCountingGroup
+ """
+ self.run_list.extend(runs)
+ self.stats = AvgStdevStats.for_runs([self.stats] + runs)
+ self.cached_bits = None
+ return self
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