How can I divide a dataset into trials using a specific delimiter?

Hello,

I have a dataset of eye-tracking data that looks like so:

Time    X       Y
192  15  NaN
499  609  519
499  608  519
.       .       .
.       .       .
.       .       .
1200    800     NaN
1201    750     600
.       .       .
.       .       .
.       .       .
2000    792     NaN

All lines between 2 consecutive NaNs correspond to a trial, I would like to create a cell array where each cell contains all the rows from one trial. Can you help me on how to procede?

Thank you

Answer 1

[Walter Roberson]

nanpos = find(isnan(YourData(:,3))]);
nanruns = diff([1 nanpos size(Yourdata,1)]);
blocks = cell2mat(YourData, nanruns, size(YourData,2));
blocks( cellfun(@isempty, blocks) ) = [];

Each of the blocks in the cell array will now start with a NaN entry, except in the case where the first entry in the array did not have a NaN, in which case the first block will include all the entries before the first NaN. Only the first block has that possibility.

If the last entry in the array is a NaN entry then the last block will be that entry by itself. I did it this way, instead of deleting the NaN, in case the NaN entry has some useful information you want to extract.

[samy rima]

Thank you for the quick reply, The second row of the code gives: Dimensions of matrices being concatenated are not consistent.

[Walter Roberson]

nanruns = diff([1; nanpos; size(Yourdata,1)]);

[samy rima]

Thank you!