ldata: Extracts signal (and annotation) data from an EDF for one or...

In remnrem/luna: Analysis of Sleep Signal Data

Extracts signal (and annotation) data from an EDF for one or more epochs

Description

Returns a data frame of signals and annotations for requested epochs

Usage

ldata(e, chs, annots = character(0))

Arguments

e	a required vector of 1-based epoch numbers corresponding to the current epoch numbering of the attached EDF
chs	a required vector of channel names to be returned, i.e. as from lchs(), all of which are required to have the same sampling rate
annots	an optional vector of annotation names to be returned, i.e. as from link{lannots}()

Value

a data frame where each row is one sample point, containing the raw signal (and annotation) data

WARNING

The following command would request all the data in an EDF (assuming that all channels have similar sampling rates) and all associated annotation information: ne <- lepoch() d <- ldata(1:ne, lchs(), lannots()) That is, for long EDFs, with a large number of channels and/or high sampling rates, the size of the data frame returned by ldata() may be large (i.e. too large), if many epochs, channels and/or annotations are requested.

Note

The returned data frame has the following columns:

• epoch number E

• elapsed time since the start of the current first epoch SEC

• any signals, in alphabetical order, where column/variable names are the channel labels, potentially sanitized if need be to remove special characters with an underscore (e.g. here EEG(sec) becomes EEG_sec_)

• any annotations, where 1 and 0 indicate the presence/absence of that annotation at that time-point

See Also

If different channels have different sampling rates, use the RESAMPLE command to resample one or more channels first, e.g. leval("RESAMPLE sig=ECG sr=125"). Otherwise it will yield an error:

Error in ldata(...) :
   requires uniform sampling rate across signals

See leval for more details.

Examples

## Not run: 
## request EEG and EMG channels, for epochs 211 and 212, along with the
## arousal annotation
> d <- ldata( 211:212 , chs = c("EEG", "EMG") , annots = "arousal" )
> head(d)
    E      SEC       EEG        EMG arousal
1 211 6300.000 -4.411765 -2.8411765       0
2 211 6300.008 -5.392157  0.8647059       0
3 211 6300.016 -4.411765 -1.6058824       0
4 211 6300.024 -4.411765 -2.8411765       0
5 211 6300.032 -6.372549  1.3588235       0
6 211 6300.040 -6.372549 -0.1235294       0


## plotting the the two signals and annotation:
> par(mfcol=c(3,1),mar=c(1,4,2,1))
> plot( d$SEC , d$EEG , type="l" , lwd=0.5 , col="darkgray",ylab="EEG")
> plot( d$SEC , d$EMG , type="l" , lwd=0.5 , col="darkgray",ylab="EMG")
> plot( d$SEC , d$arousal , type="l" , col="blue" , lwd=2,ylab="Arousal")

## End(Not run)

remnrem/luna documentation built on June 1, 2025, 2:14 p.m.