EDF writing - error when using cell array as signal DATA

Question

Wensor 2024-9-3，2:42

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2149674-edf-writing-error-when-using-cell-array-as-signal-data

评论： Wensor 2024-9-3，7:53

采纳的回答： Sandeep Mishra

Hello

I would like to do a edf file entering my signals from a cell array. I am doing a practice , mydata is

when I try to do this

>> C = {[1;2;3],[1;2;3;4],[1;2];

[4;5;6],[5;6;7;8],[3;4];

[7;8;9],[9;10;11;12],[5;6];

[10;11;12],[13;14;15;16],[7;8]}

>> hdr = edfheader("EDF");

hdr.NumSignals = 3;

hdr.NumDataRecords = 4;

hdr.DataRecordDuration = duration(0, 0, 1);

hdr.PhysicalMin = [1,1,1];

hdr.PhysicalMax = [12,16,8];

>> edfw = edfwrite('rand.edf',hdr,C);

However, I do get an error

Error using signal.internal.edf.write.validateSignalData

Expected input to be a vector

Error signal.internal.edf.write.getFileCreateOpts>checkSignals (第 223 行)

signal.internal.edf.write.validateSignalData(sigData, ...

Error signal.internal.edf.write.getFileCreateOpts>createHdr (第 96 行)

[reqhdr, sigData] = checkSignals(reqhdr, sigData, tNumSignals);

Error signal.internal.edf.write.getFileCreateOpts>createAndValidateHeader (第 47 行)

[hdr, sigData, tsal] = createHdr(thdr, sigData, tsal, hdrPropertiesList, ...

Error signal.internal.edf.write.getFileCreateOpts (第 13 行)

[hdr, sigData, tsal] = createAndValidateHeader(hdr, sigData, tsal, ...

Error edfwrite/createFile (第 1620 行)

signal.internal.edf.write.getFileCreateOpts(hdr, signalData, ...

Error edfwrite (第 499 行)

[obj, fileInfo] = createFile(obj, filename, hdr,...

Each column of my data represents a signal, and each signal is sampled at a different rate,

because I don't have specific data yet, so I did this exercise.

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Answer 1

Sandeep Mishra 2024-9-3，6:27

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2149674-edf-writing-error-when-using-cell-array-as-signal-data#answer_1509574

在 MATLAB Online 中打开

Hi Wensor,

I reviewed the code snippet and encountered a similar issue in MATLAB R2023b.

Upon further investigation, I discovered a relevant MATLAB Answers post which addresses a similar error: 

https://www.mathworks.com/matlabcentral/answers/1921840-edf-writing-error-when-using-cell-array-as-signal-data#answer_1186520

The root cause of this error is related to the input cell array 'C'. When using the ‘edfwrite’ function, if you specify a cell array as your signal data, each cell must correspond to a single signal.

However, the provided code snippet shows 'C' as a 4x3 cell array, with each cell containing vectors of varying sizes.

To resolve this issue, you can reshape the input signal 'C' to align with the expected format.

Here's a suggested approach:

% Reshaping input cell array C to C_reshaped
C_reshaped = cell(1,3); 
for col = 1:3 
    C_reshaped{col} = vertcat(C{:,col}); 
end 
% Using edfwrite with C_reshaped sigData
edfw = edfwrite('rand.edf',hdr,C_reshaped);

In the above approach, 'C_reshaped' will be a 1x3 cell array, where each column contains the concatenated results of all rows for that column, ensuring the data is structured correctly for ‘edfwrite’.