addAnnotations

Add annotations to EDF or EDF+ file

Since R2021a

Syntax

edfw = addAnnotations(edfw,tsal)

Description

edfw = addAnnotations(edfw,tsal) adds the annotations in tsal to the European Data Format (EDF) or EDF+ file.

Examples

Add Annotations to EDF File

Create a new EDF file that contains a header and a random 10-sample signal.

sig = randn(10,1);
hdr = edfheader("EDF");
hdr.NumSignals = 1;
hdr.NumDataRecords = 1;
hdr.PhysicalMin = min(sig);
hdr.PhysicalMax = max(sig);
hdr.DigitalMin = -32768;
hdr.DigitalMax = 32768;

edfw = edfwrite("random.edf",hdr,sig,"InputSampleType","physical");

Create a timetable that contains three annotations which occur at 2, 3, and 7 seconds. Specify the annotation strings as "Two", "Three", and "Seven". Each annotation duration is 1 second.

Onset = seconds([2;3;7]);
Annotations = ["Two" "Three" "Seven"]';
Duration = seconds(ones(3,1));

tsal = timetable(Onset,Annotations,Duration)

tsal=3×2 timetable
    Onset    Annotations    Duration
    _____    ___________    ________

    2 sec      "Two"         1 sec  
    3 sec      "Three"       1 sec  
    7 sec      "Seven"       1 sec  

Add the annotations to edfw. Use edfread to read the data and annotations present in the file. Plot the data and add red vertical lines at each annotation onset.

edfw = addAnnotations(edfw,tsal);
[data,anns] = edfread("random.edf");
plot(data.Signal_1{1})
xline(seconds(anns.Onset),'r')

Input Arguments

edfw — EDF or EDF+ file

edfwrite object

EDF or EDF+ file, specified as an edfwrite object.

tsal — List of timestamped annotations

timetable

List of timestamped annotations, specified as a timetable containing these variables:

• Onset — Time at which the annotation occurred, expressed as a duration indicating the number of seconds elapsed since the start time of the file. Use Onset to specify the RowTimes in the timetable.

• Annotations — A string that contains the annotation text.

• Duration — A duration scalar that indicates the duration of the event described by the annotation. If the file does not specify an annotation duration, this variable is returned as NaN.

Output Arguments

edfw — EDF or EDF+ file

edfwrite object

EDF or EDF+ file, returned as an edfwrite object.

References

[1] Kemp, Bob, Alpo Värri, Agostinho C. Rosa, Kim D. Nielsen, and John Gade. “A Simple Format for Exchange of Digitized Polygraphic Recordings.” Electroencephalography and Clinical Neurophysiology 82, no. 5 (May 1992): 391–93. https://doi.org/10.1016/0013-4694(92)90009-7.

[2] Kemp, Bob, and Jesus Olivan. "European Data Format 'plus' (EDF+), an EDF Alike Standard Format for the Exchange of Physiological Data." Clinical Neurophysiology 114, no. 9 (2003): 1755–1761. https://doi.org/10.1016/S1388-2457(03)00123-8.

Version History

Introduced in R2021a