hello
try this
this code will remove data that are contiguous and within given bounds (here 24 hrs min and 36 hours max)
the results are storedin newtime,newdata
% dummy data
samples=15*24; % 15 days by 24 hours
time= (0:samples-1);
data = max(0,randn(size(time)));
% create some y = 0 zones
data(25:60) = 0;
data(125:145) = 0;
data(225:260) = 0;
%% parameters
min_contiguous_samples = 24; % store segments only if they are at least this length
max_contiguous_samples = 36; % store segments only if they are less than this length
threshold = eps; %
%% main loop %%%%
ind = (data<threshold); % select "almost" zero data (more robust than == 0)
% now define start en end point of "unvalid" segments
[begin,ends] = find_start_end_group(ind);
length_ind = ends - begin;
ind2 = (length_ind>=min_contiguous_samples) & (length_ind<=max_contiguous_samples); % check if their length is valid
begin = begin(ind2); % selected points
ends = ends(ind2); % selected points
% define unvalid segments to be removed latter
t= [];
d = [];
idx = [];
if ~isempty(begin)
for ci = 1:length(begin)
idx = [idx (begin(ci):ends(ci))];
t= [t time(idx)];
d = [d data(idx)];
end
end
figure(1),
plot(time,data,'k',t,d,'*r');
% we can remove the unwanted data
newtime = time;
newdata = data;
newtime(idx) = [];
newdata(idx) = [];
figure(2),
plot(time,data,'k',newtime,newdata,'*b');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function [begin,ends] = find_start_end_group(ind)
% This locates the beginning /ending points of data groups
D = diff([0,ind,0]);
begin = find(D == 1);
ends = find(D == -1) - 1;
end
