Problem with edfwrite regarding the number of the signals
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Sadegh Rahimi
on 22 Jul 2022
Commented: Sadegh Rahimi
on 18 Aug 2022
Hi there,
I would like to open an EDF file in MATLAB, modify it and save it again. I expected that I could get header from edfinfo; however, it seems that I have to create header manually (only with edfheader). Am I right? But my question is about the edfwrite function. It tells me that:
Number of columns in the signal data must be equal to the number of signals.
But I have only one channel EEG and hdr.NumSignals=1. Here is the code (you can find EDF file here EDF file example):
clc;
clear all
close all
EEG_for_HFO=edfread('Rec-06.0001-GFP.edf');
header=edfinfo('Rec-06.0001-GFP.edf');
%header=get(header);
%% Inputs
EEG=EEG_for_HFO.EEG;
EEG=cell2mat(EEG);
SR=1000; % Sampling rate
% % Artifact Removal
% Threshold=1.5; % Threshold level for Artifact Removing in mili volt
% Window=10; % Length of step for Artifact Removing in mili second
% TimeDuration=100; % Time duration for Artifact Removing in mili second - Before and After
% % Highpass Filter
% FilterLevel=5; % Level of highpass filter
% Cutoff=2;
% %% Orders ------> 1 means On
% ArtifactRemoving=1;
% Filter=1;
% %% Plot
% figure;
% Time=1:length(EEG);
% plot(Time,EEG,'b');
% title('Raw signal')
% xlabel('Time(ms)');ylabel('EEG(mV)')
% %% Artifact Removal
% if (ArtifactRemoving==1)
% Start=100;
% End=Start+Window;
% for ii=1:(round(length(EEG)/Window)-Window)-1
% [Max(ii),max_indices(ii)]=max(abs(EEG(Start:End)));
% if Max(ii)>Threshold
% Before=max_indices(ii)-TimeDuration+Start;
% After=max_indices(ii)+TimeDuration-1+Start;
% EEG(Before:After)=0;
% end
%
% Start=Start+Window;
% End=End+Window;
% end
%
% hold on
% Time=1:length(EEG);
% plot(Time,EEG,'r')
% end
%
% %% Highpass Filter
% if (Filter==1)
%
% a=[];b=[];
% [b,a]=butter(FilterLevel,Cutoff/(SR/2),'high'); % Highpass filtering 2 Hz
% EEG=filtfilt(b,a,EEG);
% end
%% preparing cell
Start=1;
End=SR;
Step=SR;
EEGCell=[];
for ii=1:(length(EEG)/SR);
EEGCell{ii,1}=[EEG(Start:End)];
Start=End;
End=End+Step;
end
%% creating header
hdr=edfheader("EDF+");
hdr.Patient="Mice";
hdr.Recording="2021";
hdr.NumDataRecords=1440;
hdr.NumSignals=1;
hdr.SignalLabels="EEG";
hdr.PhysicalDimensions="mV";
hdr.PhysicalMin=-5;
hdr.PhysicalMax=5;
hdr.DigitalMin=-32256;
hdr.DigitalMax=32256;
%% exporting edf
% EEG_for_HFO.EEG=EEGCell;
% hdr.NumSignals=2;
% edfwrite('edited-Rec-06.0001-GFP.edf',hdr,EEG_for_HFO);
edfwrite('edited-Rec-06.0001-GFP.edf',hdr,EEGCell)
Accepted Answer
Walter Roberson
on 22 Jul 2022
The number of entries in the cell array is expected to be the same as the number of signals (and each entry must be a vector)
3 Comments
Phuc Nguyen
on 18 Aug 2022
I have the same problem, but I found the solution as below code:
clc, clear, close
hdr = edfheader("EDF");
hdr.Patient = "001 M 2020";
hdr.Recording = "This is the original header record";
hdr.StartTime = "00.00.01";
sig = randn(10,1); % one vector for 1 channel
hdr.NumDataRecords = 5; % 5 numbers of data recording
hdr.NumSignals = 1;
hdr.PhysicalMin = min(sig);
hdr.PhysicalMax = max(sig);
hdr.DataRecordDuration = seconds(10);
hdr.DigitalMin = -32767;
hdr.DigitalMax = 32767;
edfw = edfwrite("file.edf",hdr,sig,"InputSampleType","physical");
df = edfread('file.edf') % check edf
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