Filtering out rows based on one column and one input

Hi,

I am exploring the reasoning behind a given failure. As failures go they are sporadic and spread across a two year period.

I have merged two timetables

1) Timetable of the time of failure (0- no failure 1-failure occurs)

2) Timetable of key measured parameters measured at a 10 minute timestep over two years.

So now I have a timetable with

collumn 1 - Timstep of 10mins

Collumn 2 - Measured Parameter 1

Collumn 3 -Measured Parameter 2

Collumn 4- Measured Pararmeter 3

Collumn 5 - Failure event (0 no failure 1failure )

I am able to filter the rows with failures easily.

But I want to filter the previous 20 rows to each failure, does anyone have any suggestions how this could be best completed?

Ideally after that I would split each failure into a seperate table

Thanks

Answer 1

[Siddharth Bhutiya]

I came up with a possible solution based on your description. I am working with a 100x3 timetable that looks as follows:

     Time     Param1      Param2      Failure
    ______    _______    _________    _______

    0 min     0.63119      0.78287       0   
    10 min    0.35507      0.69379       0   
    20 min      0.997    0.0098023       0   
    30 min    0.22417      0.84321       0   
    40 min          1            1       1   
    50 min    0.60499      0.77095       0   
    60 min    0.38725      0.04266       0   
    70 min    0.14219      0.37819       0    

Code:

function failureTimetables = extractFailures(tt)
% Get the row indices for failures in the timetable
end
failureIdx = find(tt.Failure == 1);

% Create a cell array to store all the failure sub-timetables
failureTimetables = cell(numel(failureIdx),1);

for i = 1:numel(failureIdx)
    % We want to extract 20 rows before a failure but there might not be 20
    % rows if our index is less than 20, so for those extract all the rows
    % before it.
    endIdx = failureIdx(i);
    if endIdx <= 20
        startIdx = 1;
    else
        startIdx = endIdx - 20;
    end
    failureTimetables{i} = tt(startIdx:endIdx,:);
end

This would create a cell array of timetables, one sub-timetable for each failure. Hope this helps.