How do I get rid of certain values with the same X-axis value in a certain range?

Hello. I am trying to ignore/delete certain points in my data/plot. The x-axis is the time and the y-axis is the value. The time and value are both in 2 different matrices. The size of each is 8192.

If I zoom in, it looks like this.

I am trying to get rid of the value at a certain time that are more than the median within a certain range (for example +/-10).

Any ideas on how to do it?

Thank you very much!

Answer 1

[David Goodmanson]

Hi Michael,

here is one way, assuming that x (many values of which are repeated) and y are two columns.

tol = 10;
a = polyfit(x,y,1);
y1 = polyval(a,x);
ind = abs(y1-y) > tol;
x(ind) = [];
y(ind) = [];

The data appears to be very linear, so the code fits a straight line and kills off the points that are too far away from the line. This is not quite the same as a) finding the mean value of y for each group with the same x and b) killing off the points that deviate too much from each mean, but the results must be really similar.

Answer 2

[KSSV]

Put a logical conditioning, get indices and remove those points. Simple.

Example:

y = rand(1,10) ;  % random data for demo 
idx = y > 0.5 ;  % get indices of values greater than 0.5 
y(idx)= [];   % remove them from y