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librosa.util.match_events

librosa.util.match_events(events_from, events_to, left=True, right=True)

Match one set of events to another.

This is useful for tasks such as matching beats to the nearest detected onsets, or frame-aligned events to the nearest zero-crossing.

Note

A target event may be matched to multiple source events.

Parameters

events_fromndarray [shape=(n,)]

Array of events (eg, times, sample or frame indices) to match from.

events_tondarray [shape=(m,)]

Array of events (eg, times, sample or frame indices) to match against.

leftbool

rightbool

If False, then matched events cannot be to the left (or right) of source events.

Returns

event_mappingnp.ndarray [shape=(n,)]

For each event in events_from, the corresponding event index in events_to.

event_mapping[i] == arg min |events_from[i] - events_to[:]|

Raises

ParameterError

If either array of input events is not the correct shape

See also

match_intervals

Examples

>>> # Sources are multiples of 7
>>> s_from = np.arange(0, 100, 7)
>>> s_from
array([ 0,  7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91,
       98])
>>> # Targets are multiples of 10
>>> s_to = np.arange(0, 100, 10)
>>> s_to
array([ 0, 10, 20, 30, 40, 50, 60, 70, 80, 90])
>>> # Find the matching
>>> idx = librosa.util.match_events(s_from, s_to)
>>> idx
array([0, 1, 1, 2, 3, 3, 4, 5, 6, 6, 7, 8, 8, 9, 9])
>>> # Print each source value to its matching target
>>> zip(s_from, s_to[idx])
[(0, 0), (7, 10), (14, 10), (21, 20), (28, 30), (35, 30),
 (42, 40), (49, 50), (56, 60), (63, 60), (70, 70), (77, 80),
 (84, 80), (91, 90), (98, 90)]