| # Copyright 2013 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| import numbers |
| import math |
| |
| from telemetry import value as value_module |
| from telemetry.value import none_values |
| from telemetry.value import summarizable |
| |
| |
| def Variance(sample): |
| """ Compute the population variance. |
| |
| Args: |
| sample: a list of numbers. |
| """ |
| k = len(sample) - 1 # Bessel correction |
| if k <= 0: |
| return 0 |
| m = _Mean(sample) |
| return sum((x - m)**2 for x in sample)/k |
| |
| |
| def StandardDeviation(sample): |
| """ Compute standard deviation for a list of numbers. |
| |
| Args: |
| sample: a list of numbers. |
| """ |
| return math.sqrt(Variance(sample)) |
| |
| |
| def PooledStandardDeviation(list_of_samples, list_of_variances=None): |
| """ Compute standard deviation for a list of samples. |
| |
| See: https://en.wikipedia.org/wiki/Pooled_variance for the formula. |
| |
| Args: |
| list_of_samples: a list of lists, each is a list of numbers. |
| list_of_variances: a list of numbers, the i-th element is the variance of |
| the i-th sample in list_of_samples. If this is None, we use |
| Variance(sample) to get the variance of the i-th sample. |
| """ |
| pooled_variance = 0.0 |
| total_degrees_of_freedom = 0 |
| for i in xrange(len(list_of_samples)): |
| l = list_of_samples[i] |
| k = len(l) - 1 # Bessel correction |
| if k <= 0: |
| continue |
| variance = list_of_variances[i] if list_of_variances else Variance(l) |
| pooled_variance += k * variance |
| total_degrees_of_freedom += k |
| if total_degrees_of_freedom: |
| return (pooled_variance/total_degrees_of_freedom) ** 0.5 |
| return 0 |
| |
| |
| def _Mean(values): |
| return float(sum(values)) / len(values) if len(values) > 0 else 0.0 |
| |
| |
| class ListOfScalarValues(summarizable.SummarizableValue): |
| """ ListOfScalarValues represents a list of numbers. |
| |
| By default, std is the standard deviation of all numbers in the list. Std can |
| also be specified in the constructor if the numbers are not from the same |
| population. |
| """ |
| def __init__(self, page, name, units, values, |
| important=True, description=None, |
| tir_label=None, none_value_reason=None, |
| std=None, same_page_merge_policy=value_module.CONCATENATE, |
| improvement_direction=None, grouping_keys=None): |
| super(ListOfScalarValues, self).__init__(page, name, units, important, |
| description, tir_label, |
| improvement_direction, |
| grouping_keys) |
| if values is not None: |
| assert isinstance(values, list) |
| assert len(values) > 0 |
| assert all(isinstance(v, numbers.Number) for v in values) |
| assert std is None or isinstance(std, numbers.Number) |
| else: |
| assert std is None |
| none_values.ValidateNoneValueReason(values, none_value_reason) |
| self.values = values |
| self.none_value_reason = none_value_reason |
| self.same_page_merge_policy = same_page_merge_policy |
| if values is not None and std is None: |
| std = StandardDeviation(values) |
| assert std is None or std >= 0, ( |
| 'standard deviation cannot be negative: %s' % std) |
| self._std = std |
| |
| @property |
| def std(self): |
| return self._std |
| |
| @property |
| def variance(self): |
| return self._std ** 2 |
| |
| def __repr__(self): |
| if self.page: |
| page_name = self.page.display_name |
| else: |
| page_name = 'None' |
| if self.same_page_merge_policy == value_module.CONCATENATE: |
| merge_policy = 'CONCATENATE' |
| else: |
| merge_policy = 'PICK_FIRST' |
| return ('ListOfScalarValues(%s, %s, %s, %s, ' |
| 'important=%s, description=%s, tir_label=%s, std=%s, ' |
| 'same_page_merge_policy=%s, improvement_direction=%s, ' |
| 'grouping_keys=%s)') % ( |
| page_name, |
| self.name, |
| self.units, |
| repr(self.values), |
| self.important, |
| self.description, |
| self.tir_label, |
| self.std, |
| merge_policy, |
| self.improvement_direction, |
| self.grouping_keys) |
| |
| def GetBuildbotDataType(self, output_context): |
| if self._IsImportantGivenOutputIntent(output_context): |
| return 'default' |
| return 'unimportant' |
| |
| def GetBuildbotValue(self): |
| return self.values |
| |
| def GetRepresentativeNumber(self): |
| return _Mean(self.values) |
| |
| def GetRepresentativeString(self): |
| return repr(self.values) |
| |
| def IsMergableWith(self, that): |
| return (super(ListOfScalarValues, self).IsMergableWith(that) and |
| self.same_page_merge_policy == that.same_page_merge_policy) |
| |
| @staticmethod |
| def GetJSONTypeName(): |
| return 'list_of_scalar_values' |
| |
| def AsDict(self): |
| d = super(ListOfScalarValues, self).AsDict() |
| d['values'] = self.values |
| d['std'] = self.std |
| |
| if self.none_value_reason is not None: |
| d['none_value_reason'] = self.none_value_reason |
| |
| return d |
| |
| @staticmethod |
| def FromDict(value_dict, page_dict): |
| kwargs = value_module.Value.GetConstructorKwArgs(value_dict, page_dict) |
| kwargs['values'] = value_dict['values'] |
| kwargs['std'] = value_dict['std'] |
| |
| if 'improvement_direction' in value_dict: |
| kwargs['improvement_direction'] = value_dict['improvement_direction'] |
| if 'none_value_reason' in value_dict: |
| kwargs['none_value_reason'] = value_dict['none_value_reason'] |
| |
| return ListOfScalarValues(**kwargs) |
| |
| @classmethod |
| def MergeLikeValuesFromSamePage(cls, values): |
| assert len(values) > 0 |
| v0 = values[0] |
| |
| if v0.same_page_merge_policy == value_module.PICK_FIRST: |
| return ListOfScalarValues( |
| v0.page, v0.name, v0.units, |
| values[0].values, |
| important=v0.important, |
| same_page_merge_policy=v0.same_page_merge_policy, |
| none_value_reason=v0.none_value_reason, |
| improvement_direction=v0.improvement_direction, |
| grouping_keys=v0.grouping_keys) |
| |
| assert v0.same_page_merge_policy == value_module.CONCATENATE |
| return cls._MergeLikeValues(values, v0.page, v0.name, v0.tir_label, |
| v0.grouping_keys) |
| |
| @classmethod |
| def MergeLikeValuesFromDifferentPages(cls, values): |
| assert len(values) > 0 |
| v0 = values[0] |
| return cls._MergeLikeValues(values, None, v0.name, v0.tir_label, |
| v0.grouping_keys) |
| |
| @classmethod |
| def _MergeLikeValues(cls, values, page, name, tir_label, grouping_keys): |
| v0 = values[0] |
| merged_values = [] |
| list_of_samples = [] |
| none_value_reason = None |
| pooled_std = None |
| for v in values: |
| if v.values is None: |
| merged_values = None |
| none_value_reason = none_values.MERGE_FAILURE_REASON |
| break |
| merged_values.extend(v.values) |
| list_of_samples.append(v.values) |
| if merged_values: |
| pooled_std = PooledStandardDeviation( |
| list_of_samples, list_of_variances=[v.variance for v in values]) |
| return ListOfScalarValues( |
| page, name, v0.units, |
| merged_values, |
| important=v0.important, |
| description=v0.description, |
| tir_label=tir_label, |
| same_page_merge_policy=v0.same_page_merge_policy, |
| std=pooled_std, |
| none_value_reason=none_value_reason, |
| improvement_direction=v0.improvement_direction, |
| grouping_keys=grouping_keys) |