Cleaning noisy data from a plot

Hi;

I have a regular linear plot from a sensor, but there are some spikes that shouldn't exist actually. I want to eject points that cause these spikes and interpolate the interspaced part. Is there any apps or tools that will help me on it, or shall I build an algorithm which will find these points and eject them?

Thank you in advance.

Answer 1

[Star Strider]

If you have the Signal Processing Toolbox, the findpeaks function (with appropriate name-value pair argument choices and parameters) could help you identify the spikes and their locations.

Keep your original independent variable vector, since you’ll need it for the interpolation. Then use the location index vector provided by findpeaks to eliminate them. Then interpolate.

To illustrate:

x = 1:100;                                      % Create Data
y = 1 + 0.1*x.*rand(1,100);                     % Create Data
spikes = randi(100, 1, 5);                      % Create Data
y(spikes) = randi(50, 1, 5);                    % Create Data

[spk,loc] = findpeaks(y,'MinPeakHeight',10);    % Find ‘spikes’
xorg = x;                                       % Save Original ‘x’
yorg = y;                                       % Save Original ‘y’
x(loc) = [];                                    % Eliminate ‘spikes’ From Data
y(loc) = [];                                    % Eliminate ‘spikes’ From Data

yint = interp1(x, y, xorg);                     % Interpolate Missing Data

figure(1)
subplot(2,1,1)
plot(xorg, yorg)
grid
title('Original Data')
yl = get(gca, 'YLim')
subplot(2,1,2)
plot(xorg, yint)
grid
title('Interpolated Data Without Spikes')
set(gca, 'YLim',yl)