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"""Classes and functions for dealing with video statistics.
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Future interface ideas:
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* Display certain records, or a range of records (records 1-10; last 15 records;
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records with a certain field (or any field) matching given text/regexp
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* Display formatted output of all records, or a selection of records,
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with control over which fields are displayed
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# Order of fields in stats.tovid
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'length', # a.k.a. CUR_LENGTH
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'encoding_time', # SCRIPT_TOT_TIME
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# Integer numeric fields
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"""A list of statistics that may be queried with a simple database-like
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def __init__(self, records=None, filename=''):
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"""Create a Statlist, using the given list of records, or by reading
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from the given filename (CSV text).
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# Use provided records, if any
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self.records = copy(records)
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# Otherwise, read from any provided filename
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if filename is not '':
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self.read_csv(filename)
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def read_csv(self, filename):
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"""Import stats from a CSV (comma-delimited quoted text) file."""
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statfile = open(filename, 'r')
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csv_reader = csv.DictReader(statfile, FIELDS, skipinitialspace=True)
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for line in csv_reader:
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# Convert some string and numeric fields
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line['format'] = str.lower("%s" % line['format'])
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line['tvsys'] = str.lower("%s" % line['tvsys'])
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for field in int_fields:
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num = int("%s" % line[field])
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except ValueError, TypeError:
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self.records.append(line)
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print "Read %s lines from %s" % (len(self.records), filename)
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def unique(self, field):
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"""Return a list of unique values of the given field."""
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for record in self.records:
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if record[field] not in unique_values:
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unique_values.append(record[field])
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def count_unique(self, field):
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"""Count the occurrences of each unique value of the given field.
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Return a dictionary of unique values and the number of occurrences
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# Go through all records and total up occurrences of each value
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for record in self.records:
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value = record[field]
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if value is None or value == '':
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elif value not in counts:
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def average(self, attribute):
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"""Calculate the average value for a given numeric VidStat attribute.
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For example, average('bitrate') returns the average overall bitrate of
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all videos in the list."""
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# Error if attribute is non-numeric
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if attribute not in int_fields:
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print "Can't average %s: not defined as a numeric field"
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for record in self.records:
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# Only append non-zero values
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if record[attribute] != 0:
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values.append(record[attribute])
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return float(sum(values) / len(values))
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def average_by(self, attribute, by_attribute):
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"""Return a dictionary of averages of an attribute, indexed by another
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attribute. For example, average_by('bitrate', 'format') returns average
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bitrates for each format."""
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# Error if attribute is non-numeric
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if attribute not in int_fields:
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print "Can't average %s: not defined as a numeric field"
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values_by = self.list_by(attribute, by_attribute)
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# Calculate averages for each value-list
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if len(values_by) > 0:
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for key, samples in values_by.iteritems():
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averages[key] = float(sum(samples) / len(samples))
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except ZeroDivisionError:
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def list_by(self, attribute, by_attribute, sort_lists=False):
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"""Return a dictionary of lists of values of the given attribute,
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indexed by another attribute. If sort_lists is True, sort all lists."""
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# Create a dictionary of value-lists, indexed by by_attribute
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for record in self.records:
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byval = record[by_attribute]
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if not values_by.has_key(byval):
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values_by[byval] = []
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# Only include non-zero values
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if record[attribute] != 0:
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values_by[byval].append(record[attribute])
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for index in values_by.iterkeys():
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values_by[index].sort()
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def get_matching(self, attribute, value):
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"""Return a list of records where the given attribute equals the given
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value. Records are field-indexed dictionaries of values.
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# List of matching records
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for record in self.records:
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if record[attribute] == value:
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matches.append(record)
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def length(self, field):
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"""Return the length of the longest record in the given field, or the
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width of the field name itself, whichever is greater."""
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for record in self.records:
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cur_len = len(str(record[field]))
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if cur_len > longest:
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def show(self, show_records='all', show_fields=FIELDS):
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"""Print records matching given criteria, showing only the given fields.
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show_records: Number of record to show, or range of numbers
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show_fields: List of fields, by name as shown in FIELDS
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# Remember field sizes (character widths)
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# Create field headings
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for field in show_fields:
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size[field] = self.length(field)
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heading += "%s " % str.ljust(field, size[field])
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print "Error: field '%s' does not exist" % field
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# Print fields from matching records
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for record in self.records:
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# TODO: support show_records
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for field in show_fields:
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line += "%s " % str.ljust(str(record[field]), size[field])
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# Print heading at end too
b'\\ No newline at end of file'
added
removed
libtovid/stats.py
