[Eeglablist] systematically deleting data

[Yamil Vidal Dos Santos]

Ciao Brittany,
If you want to know the length in seconds of your data, that is easy to
calculate.
The structure in MATLAB that contains the data is EEG.data . It has
dimensions electrode x time x trial (or just electrode x time for
continuous data). The dimension time is as long as the total amount of
samples, so if you want to know the total length of your data in seconds,
that would be:

length_in_secs = size( EEG.data , 2 ) / EEG.srate;

This is just dividing the length of your data in samples by your sampling
rate.

The function pop_select also accepts samples instead of time, so you could
just do:

EEG = pop_select(EEG, 'point', [size( EEG.data , 2 ) - EEG.srate*600 ,
size( EEG.data , 2 )] );

That will keep only the last 600 secs, regardless of the actual length of
the data.

I hope you find this useful.
Best,
Yamil


On Fri, Oct 31, 2014 at 11:22 PM, Brittany Alperin <balperin07 at gmail.com>
wrote:

> Hello
>
> I want to cut all of my datasets down to just include the last 600 seconds
> and I also want to write some code to automate this.
>
> Is there a way I can find out the length without manually plotting the
> data to find out how long the file is? I assume I'll use the select data
> function (pop_select), but all I know how to do is put in actual numerical
> values. Using this method I would have to plot each dataset, find out the
> length, and subtract 600 seconds from that, which is a bit tedious and
> wouldn't allow me to automate it.
>
> Basically, is there a Matlab function that will tell me how many seconds
> long the file is? Can you enter something other than numbers in the
> pop_select window?\
>
> Thanks,
> Brittany
>
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