Brilliant, thanks Derek. Scott
On 05/05/2012, at 8:36 AM, Derek Lamb wrote: > Hi Scott, > > Assuming your $t is always increasing (you can qsort() it if it's not), you > can assemble a vector of delta-t's, and if you're only interested in integer > offsets, use the hist function to generate a histogram of sorts: > > $dt = $t(1:-1) - $t(0:-2); > ($interval,$number) = hist($dt,$dt->min-0.5,$dt->max+0.5,1); > p $interval,$number; > p $number->where($interval==50); > > Now you have one piddle that contains a list of the integer offsets, and > another piddle that tells you the frequency. If you have non-integer times, > then that will require some more thought as to how close two differences can > be and be considered the same. > > I've also discovered that Maggie's PDL::Stats (available from CPAN) might > have things that help with the time-series analysis you seem to be doing (see > the PDL::Stats::TS module). For example, I recently had to take a moving > average of a time series of data, then compute the point-to-point differences > of that moving average, and it was as simple as: > > use PDL::Stats; > $data->filter_ma(3)->diff; > > best, > Derek > > On May 4, 2012, at 4:17 PM, Scott Penrose wrote: > >> Good morning >> >> I have a piddle with time stems, e.g. >> >> print $t; >> [ 100, 150, 200, 249, 300 ]; >> >> The data is really long and obviously the example above is made up. >> >> Anyway I want to calculate the number between and calculate, so from the >> data above I would have >> >> 50 = 2 >> 49 = 1 >> 51 = 1 >> >> The main reason I am doing this is to make sure that my measurements are on >> the window (in this case 50 ms) and how many are not. >> >> Currently I just did it by hand, keeping the last value and iterating >> through all the data in a loop. But it didn't feel very PDL way. What is the >> better way? >> >> Ta >> >> Scott >> >> >> _______________________________________________ >> Perldl mailing list >> [email protected] >> http://mailman.jach.hawaii.edu/mailman/listinfo/perldl >> > _______________________________________________ Perldl mailing list [email protected] http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
