Write the Timetable data to the EDF file
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Hi @Wensor ,
You asked, “How can I write a Timetable data into a EDF File?”
To address your inquiry regarding writing a Timetable to an EDF file in MATLAB, I broke down your requirements and analyzed the provided code.
Data Structure: You are working with a Timetable (TT) containing signal data. EDF File Format: You are attempting to write this data to an EDF file using the edfwrite function. Error Handling: The error indicates that annotations are expected as a two-column array, but you do not have any annotations to include.
So, to write your Timetable data into an EDF file without annotations, you need to make that the data structure and the header properties are correctly set up based on mathworks documentation provided in the link below.
https://www.mathworks.com/help/signal/ref/edfwrite.html
Below is the complete and corrected code based on your original snippet.
% Create your Timetable data time = duration(0, 0, 0.1*(0:6)'); % Create a duration vector for time data1 = randn(length(time), 1); % Signal 1 data2 = randn(length(time), 1); % Signal 2 data3 = randn(length(time), 1); % Signal 3
% Create a timetable TT = timetable(time, data1, data2, data3);
% Prepare the EDF Header
hdr = edfheader("EDF");
hdr.NumSignals = 3; % Number of signals
hdr.NumDataRecords = height(TT); % Number of data records
hdr.DataRecordDuration = duration(0, 0, 0.1); % Duration of each data record
% Specify signal labels and other properties hdr.SignalLabels = ["Signal 1"; "Signal 2"; "Signal 3"]; hdr.TransducerTypes = ["EEG"; "EEG"; "EEG"]; % Example transducer type hdr.PhysicalDimensions = ["uV"; "uV"; "uV"]; % Signal units hdr.PhysicalMin = [-500; -500; -500]; % Min physical values hdr.PhysicalMax = [500; 500; 500]; % Max physical values hdr.DigitalMin = [-32768; -32768; -32768]; % Min digital values hdr.DigitalMax = [32767; 32767; 32767]; % Max digital values
% Prepare signal data sigdata = [TT.data1, TT.data2, TT.data3]; % Extract signal data from the timetable
% Write to EDF file without annotations
edfw = edfwrite("rand.edf", hdr, sigdata); % Correct method call
Please see attached.
If you later decide to include annotations, you would need to create a separate timetable for them, ensuring it contains the required columns: Onset, Annotations, and Duration. Make sure that the length of the sigdata matches the number of data records in the header.
Hope this answers your questions please let me know if you have any further questions.
4 个评论
Hi @Wensor,
Thanks for sharing this code, now it makes it easier to achieve your task. So,what you need to do is to extract the relevant data from the Timetable into a suitable format. Here's a step-by-step approach to correctly achieve this
Extract Signal Data: You will extract the measurement variables from your Timetable and convert the time information into a numeric representation (e.g., seconds since the start).
Prepare the EDF Header: Using edfheader, you will set up the EDF file structure, specifying the number of signals and other required metadata.
Write to EDF File: Finally, you will call edfwrite with the prepared header and signal data.
Here's a complete and corrected version of your MATLAB code:
% Create your Timetable data
MeasurementTime = datetime({'2015-12-18 08:03:05';'2015-12-18
10:03:17';'2015-12-18 12:03:13'});
Temp = [37.3; 39.1; 42.3];
Pressure = [30.1; 30.03; 29.9];
WindSpeed = [13.4; 6.5; 7.3];
TT = timetable(MeasurementTime, Temp, Pressure, WindSpeed);
% Convert MeasurementTime to numeric value (seconds since start) startTime = TT.MeasurementTime(1); timeInSeconds = seconds(TT.MeasurementTime - startTime);
% Prepare the EDF Header
hdr = edfheader("EDF");
hdr.NumSignals = 3; % Number of signals
hdr.NumDataRecords = height(TT); % Number of data records
hdr.DataRecordDuration = seconds(1); % Example: 1 second duration
% Specify signal labels and other properties hdr.SignalLabels = ["Temperature"; "Pressure"; "Wind Speed"]; hdr.TransducerTypes = ["Temp Sensor"; "Pressure Sensor"; "Anemometer"]; hdr.PhysicalDimensions = ["°C"; "hPa"; "m/s"]; hdr.PhysicalMin = [0; 0; 0]; % Adjust these based on your data range hdr.PhysicalMax = [50; 110; 20]; % Adjust these based on your data range hdr.DigitalMin = [-32768; -32768; -32768]; % Min digital values hdr.DigitalMax = [32767; 32767; 32767]; % Max digital values
% Prepare signal data sigdata = [TT.Temp, TT.Pressure, TT.WindSpeed]; % Extract signals from the timetable
% Write to EDF file without annotations
edfw = edfwrite("measurements.edf", hdr, sigdata); % Correct
method call
Please let me know if this helped resolve your problem.
Hi @Wensor,
I have executed the code above and attached the file below. Please let me know if this answers your question.
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