Created
August 25, 2015 11:00
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| import collections | |
| import csv | |
| Interval = collections.namedtuple('Interval', 'start end track') | |
| Switch = collections.namedtuple('Switch', 'timestamp track') | |
| class Intervals(object): | |
| def __init__(self, default_track): | |
| self._default_track = default_track | |
| self._switches = [Switch(0, default_track)] | |
| def __iter__(self): | |
| return iter(self._switches) | |
| def _delete(self, start, end): | |
| ''' | |
| Delete all switches that occur between | |
| start (inclusive) and end (exclusive). | |
| O(#switches_inside) | |
| ''' | |
| self._switches = [switch for switch in self._switches | |
| if not (start <= switch.timestamp < end)] | |
| def _insert(self, new_switch): | |
| ''' | |
| Insert a new switch (overriding if there was one at the same time). | |
| O(#switches_inside) | |
| ''' | |
| for i, switch in enumerate(self._switches): | |
| if switch.timestamp == new_switch.timestamp: | |
| self._switches[i] = new_switch | |
| return | |
| elif switch.timestamp > new_switch.timestamp: | |
| self._switches.insert(i, new_switch) | |
| return | |
| self._switches.append(new_switch) | |
| def track_at(self, timestamp): | |
| ''' | |
| Return track name that should be played at timestamp. | |
| O(#switches_inside) | |
| ''' | |
| result = self._default_track | |
| for switch in self._switches: | |
| if switch.timestamp > timestamp: | |
| break | |
| result = switch.track | |
| return result | |
| def insert(self, interval): | |
| ''' | |
| Insert new interval. | |
| O(#switches_inside) | |
| ''' | |
| after_interval_track = self.track_at(interval.end) | |
| self._delete(interval.start, interval.end) | |
| self._insert(Switch(interval.start, interval.track)) | |
| self._insert(Switch(interval.end, after_interval_track)) | |
| csv_example = '''\ | |
| A,0,10 | |
| E,15,35 | |
| D,30,40 | |
| C,20,30 | |
| B,10,20''' | |
| if __name__ == '__main__': | |
| intervals_list = [] | |
| for row in csv.reader(csv_example.split('\n')): | |
| intervals_list.append(Interval(start=int(row[1]), | |
| end=int(row[2]), | |
| track=row[0])) | |
| intervals = Intervals(intervals_list[0].track) | |
| for interval in reversed(intervals_list): | |
| intervals.insert(interval) | |
| print list(intervals) | |
| A, B, C, D, E = ('A', 'B', 'C', 'D', 'E') | |
| def test(intervals, result): | |
| changes = Intervals(A) | |
| for interval in intervals: | |
| changes.insert(interval) | |
| if changes._switches != result: | |
| print 'FAIL' | |
| print intervals | |
| print result | |
| print changes._switches | |
| test([Interval(10, 20, B)], | |
| [(0, A), (10, B), (20, A)]) | |
| test([Interval(10, 20, B), Interval(5, 9, C)], | |
| [(0, A), (5, C), (9, A), (10, B), (20, A)]) | |
| test([Interval(10, 20, B), Interval(5, 10, C)], | |
| [(0, A), (5, C), (10, B), (20, A)]) | |
| test([Interval(10, 20, B), Interval(5, 11, C)], | |
| [(0, A), (5, C), (11, B), (20, A)]) | |
| test([Interval(10, 20, B), Interval(20, 30, C), | |
| Interval(30, 40, D), Interval(15, 35, E)], | |
| [(0, A), (10, B), (15, E), (35, D), (40, A)]) |
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