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_from : ndarray [shape=(n,)]

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

events_to : ndarray [shape=(m,)]

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

left : bool

right : bool

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

Returns:

event_mapping : np.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)]