Subtract I0 from subsequent timetable values

2021 2 17
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更新时间：2021 2 17
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I have a timetable with different variables corresponding to measurements made with an instrument. One of the variables is a logic variable, "Valve State" that indicates whether the measurement is meant for a background or is a sample measurement.
How could I iterate through the time table and find the most recent variable with "Valve State" == 1 and use that for the calculation on the next chunk of rows which have a "Valve State" == 0?

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Walter Roberson
Walter Roberson 2021-2-17

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measurement(valve_state == 0) = nan;
fillmissing(measurement, 'previous')

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Poison Idea fan
Poison Idea fan 2021-2-17
编辑：Poison Idea fan 2021-2-17
This works for how I wrote the question, but I wrote the question poorly. I don't need to get rid of the valve_state == 0 values, rather I need to take value(valve_state == 0) - value(valve_state == 1). The values are in a cycle where valve_state == 1 for 10 minutes and then it switches to valve_state == 0 for 30 minutes. When valve_state == 0 I need to use the most recent set of valve_state == 1 for the calculation.
I appreciate the quick response. I am new to Answers.
Walter Roberson
Walter Roberson 2021-2-17
If you do
VSR = reshape(valve_state, 1, []); %need a row
mask = VSR == 0;
start0 = strfind([0 mask], [0 1]);
stop0 = strfind([mask 0], [1 0]);
Now start0(K) marks the start of a run of 0's and stop0(K) marks the end of the same run. Under the assumption that the first datapoint is a 1 rather than 0, you would use the datapoint at start0(K)-1 . So perhaps something like
basevalue = measurement;
if start0(1) == 1
basevalue(1:stop0(1)) = something; %this is the case where the valve started 0
start0(1) = []; stop0(1) = [];
end
for K = 1 : length(start0)
basevalue(start0(K):stop0(K)) = basevalue(start0(K)-1);
end
Poison Idea fan
Poison Idea fan 2021-2-17
This is very helpful thank you! I couldn't figure out a way to isolate the run of 0's and what not.

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