class Histogram(StatsFilter):
""" Generate a basic histogram of the specified field. The value() method
returns a dict of value to occurance count mappings. The __str__ method
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)
if hasattr(collections, 'Counter'):
self._counter = collections.Counter()
else:
self._counter = FallbackCounter()
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"
for key, count in occurences:
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)
def __init__(self, field, **kwargs):
super(Histogram, self).__init__(field, **kwargs)
if hasattr(collections, 'Counter'):
self._counter = collections.Counter()
else:
self._counter = FallbackCounter()
