如何在Python中重塑和聚合元组列表?

如果您是从数据库中获取的,为什么不让查询首先执行它呢?比如: SELECT hour, location, COUNT(*) FROM events GROUP BY hour, location ORDER BY hour, location .

在Python中,可能是这样的:

timed_events = {}
# Count them up
for event in events_from_database:
    timed_events[event] = timed_events.setdefault(event, 0) + 1

# Form a new list with the original data plus the count
aggregate_list = [(evt[0], evt[1], count) for evt,count in events.items()]

有点像……:

import collections

raw_data = [(1, 0), (1, 0), (1, 1), (2, 1), (2, 2), (2, 2), (2, 2)]
aux = collections.defaultdict(int)
for x, y in raw_data:
  aux[x, y] += 1

locations = sorted(set(x for x, y in raw_data))
hours = sorted(set(y for x, y in raw_data))
result = [(x, y, aux[x, y]) for x in locations for y in hours]

如果您希望位置和时间反映原始数据中的内容。你可能想用 range(some, thing) 对于每个地点和时间,如果你有关于地点和时间应该跨越的范围的独立信息,那么你就应该这样做,与实际发生的时间和地点完全不同 raw_data .