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make int casting explicit

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This commit is contained in:
Jeremy Carbaugh 2012-03-11 22:19:15 -07:00
parent fad10e5a98
commit de72f7755c
1 changed files with 46 additions and 46 deletions
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92
saucebrush/stats.py
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@ -5,7 +5,7 @@ import math
def _average(values):
""" Calculate the average of a list of values.
:param values: an iterable of ints or floats to average
"""
value_count = len(values)
@ -14,64 +14,64 @@ def _average(values):
def _median(values):
""" Calculate the median of a list of values.
:param values: an iterable of ints or floats to calculate
"""
count = len(values)
# bail early before sorting if 0 or 1 values in list
if count == 0:
return None
elif count == 1:
return values[0]
values = sorted(values)
if count % 2 == 1:
# odd number of items, return middle value
return float(values[count / 2])
return float(values[int(count / 2)])
else:
# even number of items, return average of middle two items
mid = count / 2
mid = int(count / 2)
return sum(values[mid - 1:mid + 1]) / 2.0
def _stddev(values, population=False):
""" Calculate the standard deviation and variance of a list of values.
:param values: an iterable of ints or floats to calculate
:param population: True if values represents entire population,
False if it is a sample of the population
"""
avg = _average(values)
count = len(values) if population else len(values) - 1
# square the difference between each value and the average
diffsq = ((i - avg) ** 2 for i in values)
# the average of the squared differences
variance = sum(diffsq) / float(count)
return (math.sqrt(variance), variance) # stddev is sqrt of variance
class StatsFilter(Filter):
""" Base for all stats filters.
"""
def __init__(self, field, test=None):
self._field = field
self._test = test
def process_record(self, record):
if self._test is None or self._test(record):
self.process_field(record[self._field])
return record
def process_field(self, record):
raise NotImplementedError('process_field not defined in ' +
self.__class__.__name__)
def value(self):
raise NotImplementedError('value not defined in ' +
self.__class__.__name__)
@ -80,14 +80,14 @@ class Sum(StatsFilter):
""" Calculate the sum of the values in a field. Field must contain either
int or float values.
"""
def __init__(self, field, initial=0, **kwargs):
super(Sum, self).__init__(field, **kwargs)
self._value = initial
def process_field(self, item):
self._value += item or 0
def value(self):
return self._value
@ -95,35 +95,35 @@ class Average(StatsFilter):
""" Calculate the average (mean) of the values in a field. Field must
contain either int or float values.
"""
def __init__(self, field, initial=0, **kwargs):
super(Average, self).__init__(field, **kwargs)
self._value = initial
self._count = 0
def process_field(self, item):
if item is not None:
self._value += item
self._count += 1
def value(self):
return self._value / float(self._count)
class Median(StatsFilter):
""" Calculate the median of the values in a field. Field must contain
either int or float values.
**This filter keeps a list of field values in memory.**
"""
def __init__(self, field, **kwargs):
super(Median, self).__init__(field, **kwargs)
self._values = []
def process_field(self, item):
if item is not None:
self._values.append(item)
def value(self):
return _median(self._values)
@ -131,19 +131,19 @@ class MinMax(StatsFilter):
""" Find the minimum and maximum values in a field. Field must contain
either int or float values.
"""
def __init__(self, field, **kwargs):
super(MinMax, self).__init__(field, **kwargs)
self._max = None
self._min = None
def process_field(self, item):
if item is not None:
if self._max is None or item > self._max:
self._max = item
if self._min is None or item < self._min:
self._min = item
def value(self):
return (self._min, self._max)
@ -156,24 +156,24 @@ class StandardDeviation(StatsFilter):
**This filter keeps a list of field values in memory.**
"""
def __init__(self, field, **kwargs):
super(StandardDeviation, self).__init__(field, **kwargs)
self._values = []
def process_field(self, item):
if item is not None:
self._values.append(item)
def average(self):
return _average(self._values)
def median(self):
return _median(self._values)
def value(self, population=False):
""" Return a tuple of (standard_deviation, variance).
:param population: True if values represents entire population,
False if values is a sample. Default: False
"""
@ -185,34 +185,34 @@ class Histogram(StatsFilter):
generates a basic and limited histogram useful for printing to the
command line. The label_length attribute determines the padding and
cut-off of the basic histogram labels.
**This filters maintains a dict of unique field values in memory.**
"""
label_length = 6
def __init__(self, field, **kwargs):
super(Histogram, self).__init__(field, **kwargs)
self._counter = collections.Counter()
def process_field(self, item):
self._counter[self.prep_field(item)] += 1
def prep_field(self, item):
return item
def value(self):
return self._counter.copy()
def in_order(self):
ordered = []
for key in sorted(self._counter.keys()):
ordered.append((key, self._counter[key]))
return ordered
def most_common(self, n=None):
return self._counter.most_common(n)
@classmethod
def as_string(self, occurences, label_length):
output = "\n"
@ -220,6 +220,6 @@ class Histogram(StatsFilter):
key_str = str(key).ljust(label_length)[:label_length]
output += "%s %s\n" % (key_str, "*" * count)
return output
def __str__(self):
return Histogram.as_string(self.in_order(), label_length=self.label_length)