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133 lines
4.5 KiB
133 lines
4.5 KiB
#
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# Copyright (C) 2013 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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"""Histogram generation tools."""
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from __future__ import absolute_import
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from __future__ import division
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from collections import defaultdict
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from update_payload import format_utils
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class Histogram(object):
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"""A histogram generating object.
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This object serves the sole purpose of formatting (key, val) pairs as an
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ASCII histogram, including bars and percentage markers, and taking care of
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label alignment, scaling, etc. In addition to the standard __init__
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interface, two static methods are provided for conveniently converting data
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in different formats into a histogram. Histogram generation is exported via
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its __str__ method, and looks as follows:
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Yes |################ | 5 (83.3%)
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No |### | 1 (16.6%)
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TODO(garnold) we may want to add actual methods for adding data or tweaking
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the output layout and formatting. For now, though, this is fine.
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"""
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def __init__(self, data, scale=20, formatter=None):
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"""Initialize a histogram object.
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Args:
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data: list of (key, count) pairs constituting the histogram
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scale: number of characters used to indicate 100%
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formatter: function used for formatting raw histogram values
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"""
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self.data = data
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self.scale = scale
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self.formatter = formatter or str
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self.max_key_len = max([len(str(key)) for key, count in self.data])
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self.total = sum([count for key, count in self.data])
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@staticmethod
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def FromCountDict(count_dict, scale=20, formatter=None, key_names=None):
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"""Takes a dictionary of counts and returns a histogram object.
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This simply converts a mapping from names to counts into a list of (key,
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count) pairs, optionally translating keys into name strings, then
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generating and returning a histogram for them. This is a useful convenience
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call for clients that update a dictionary of counters as they (say) scan a
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data stream.
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Args:
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count_dict: dictionary mapping keys to occurrence counts
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scale: number of characters used to indicate 100%
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formatter: function used for formatting raw histogram values
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key_names: dictionary mapping keys to name strings
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Returns:
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A histogram object based on the given data.
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"""
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namer = None
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if key_names:
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namer = lambda key: key_names[key]
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else:
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namer = lambda key: key
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hist = [(namer(key), count) for key, count in count_dict.items()]
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return Histogram(hist, scale, formatter)
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@staticmethod
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def FromKeyList(key_list, scale=20, formatter=None, key_names=None):
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"""Takes a list of (possibly recurring) keys and returns a histogram object.
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This converts the list into a dictionary of counters, then uses
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FromCountDict() to generate the actual histogram. For example:
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['a', 'a', 'b', 'a', 'b'] --> {'a': 3, 'b': 2} --> ...
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Args:
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key_list: list of (possibly recurring) keys
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scale: number of characters used to indicate 100%
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formatter: function used for formatting raw histogram values
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key_names: dictionary mapping keys to name strings
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Returns:
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A histogram object based on the given data.
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"""
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count_dict = defaultdict(int) # Unset items default to zero
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for key in key_list:
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count_dict[key] += 1
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return Histogram.FromCountDict(count_dict, scale, formatter, key_names)
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def __str__(self):
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hist_lines = []
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hist_bar = '|'
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for key, count in self.data:
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if self.total:
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bar_len = count * self.scale // self.total
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hist_bar = '|%s|' % ('#' * bar_len).ljust(self.scale)
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line = '%s %s %s' % (
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str(key).ljust(self.max_key_len),
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hist_bar,
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self.formatter(count))
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percent_str = format_utils.NumToPercent(count, self.total)
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if percent_str:
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line += ' (%s)' % percent_str
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hist_lines.append(line)
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return '\n'.join(hist_lines)
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def GetKeys(self):
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"""Returns the keys of the histogram."""
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return [key for key, _ in self.data]
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