MATLAB: Find beginning and end of a series of events

data analysisfeature extraction

Hi I have a log file that captures events with a timestamp. When no event occurs nothing is logged, meaning there is no continuous time stamp data. My goal is to identify when each "usage session" starts and ends based on some criterion: e.g. no event occurred for x hours. Is there an easy way to identify start/end through matlab?
Example data set (1st col: timestamp, 2nd/3rd: event)
    [   59.2945]    '00070051'    'Down'  
    [   59.4056]    '00070051'    'Down'  
    [   59.6964]    '00070051'    'Down'  
    [   59.8762]    '00070051'    'Down'  
    [   59.9439]    '00070051'    'Down'  
    [   60.0577]    '00070051'    'Down'  
    [   61.0465]    '00070051'    'Down'  
    [   61.1140]    '00070051'    'Down'  
    [   61.2269]    '00070051'    'Down'  
    [   61.3165]    '00070051'    'Down'  
    [   61.4064]    '00070051'    'Down'  
    [   61.5191]    '00070051'    'Down'  
    [   61.6088]    '00070051'    'Down'  
    [   61.7668]    '00070051'    'Down'  
    [   61.8563]    '00070051'    'Down'  
    [   61.9915]    '00070051'    'Down'  
    [   62.1038]    '00070051'    'Down'  
    [   62.2181]    '00070051'    'Down'  
    [   62.3292]    '00070051'    'Down'  
    [   62.4416]    '00070051'    'Down'  
    [   62.5540]    '00070051'    'Down'  
    [   62.6663]    '00070051'    'Down'  
    [   62.7564]    '00070051'    'Down'  
    [   62.8914]    '00070051'    'Down'  
    [  135.5951]    '000c0223'    'Home'  
    [  135.7017]    '000c0223'    'Home'  
    [  142.2507]    '0007004f'    'Right' 
    [  142.3606]    '0007004f'    'Right' 
    [  142.4056]    '0007004f'    'Right' 
    [  142.5180]    '0007004f'    'Right' 
    [  142.5855]    '0007004f'    'Right' 
    [  142.6978]    '0007004f'    'Right' 
    [  142.7430]    '0007004f'    'Right' 
    [  142.8557]    '0007004f'    'Right' 
    [  142.9018]    '0007004f'    'Right' 
    [  143.0128]    '0007004f'    'Right' 
    [  143.1928]    '00070058'    'Select'
    [  143.3054]    '00070058'    'Select'
    [  144.4978]    '00070051'    'Down'  
    [  144.5890]    '00070051'    'Down'  
    [  144.7921]    '0007004f'    'Right' 
    [  144.9256]    '0007004f'    'Right' 
    [  144.9704]    '0007004f'    'Right' 
    [  145.1065]    '0007004f'    'Right'

Best Answer

My first thought is to use diff on the timestamps (to get the time between events) and then threshold the results (anything over a certain time is the start of a new session).
How long are the gaps between each session relative to the inner-event interval within a session?
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