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112 lines
3.6 KiB
Python
112 lines
3.6 KiB
Python
# This file is part of beets.
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# Copyright 2016, Philippe Mongeau.
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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"""Get a random song or album from the library."""
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import random
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from itertools import groupby
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from operator import attrgetter
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def _length(obj, album):
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"""Get the duration of an item or album."""
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if album:
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return sum(i.length for i in obj.items())
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else:
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return obj.length
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def _equal_chance_permutation(objs, field="albumartist", random_gen=None):
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"""Generate (lazily) a permutation of the objects where every group
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with equal values for `field` have an equal chance of appearing in
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any given position.
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"""
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rand = random_gen or random
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# Group the objects by artist so we can sample from them.
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key = attrgetter(field)
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objs.sort(key=key)
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objs_by_artists = {}
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for artist, v in groupby(objs, key):
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objs_by_artists[artist] = list(v)
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# While we still have artists with music to choose from, pick one
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# randomly and pick a track from that artist.
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while objs_by_artists:
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# Choose an artist and an object for that artist, removing
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# this choice from the pool.
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artist = rand.choice(list(objs_by_artists.keys()))
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objs_from_artist = objs_by_artists[artist]
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i = rand.randint(0, len(objs_from_artist) - 1)
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yield objs_from_artist.pop(i)
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# Remove the artist if we've used up all of its objects.
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if not objs_from_artist:
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del objs_by_artists[artist]
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def _take(iter, num):
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"""Return a list containing the first `num` values in `iter` (or
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fewer, if the iterable ends early).
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"""
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out = []
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for val in iter:
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out.append(val)
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num -= 1
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if num <= 0:
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break
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return out
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def _take_time(iter, secs, album):
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"""Return a list containing the first values in `iter`, which should
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be Item or Album objects, that add up to the given amount of time in
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seconds.
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"""
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out = []
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total_time = 0.0
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for obj in iter:
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length = _length(obj, album)
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if total_time + length <= secs:
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out.append(obj)
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total_time += length
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return out
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def random_objs(
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objs, album, number=1, time=None, equal_chance=False, random_gen=None
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):
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"""Get a random subset of the provided `objs`.
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If `number` is provided, produce that many matches. Otherwise, if
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`time` is provided, instead select a list whose total time is close
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to that number of minutes. If `equal_chance` is true, give each
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artist an equal chance of being included so that artists with more
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songs are not represented disproportionately.
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"""
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rand = random_gen or random
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# Permute the objects either in a straightforward way or an
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# artist-balanced way.
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if equal_chance:
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perm = _equal_chance_permutation(objs)
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else:
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perm = objs
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rand.shuffle(perm) # N.B. This shuffles the original list.
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# Select objects by time our count.
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if time:
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return _take_time(perm, time * 60, album)
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else:
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return _take(perm, number)
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