how to find a window of days in a time series data with values in a range

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nlm 2020-5-1

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关闭： MATLAB Answer Bot 2021-8-20

I have a time series data from which I need to find a window of days where the start value is >0.4 and end value is <0.2. However, the values in that window range between 0.4 and 0.2. I have this so far. However, my code is finding all values which have a decreasing trend for 10 days.

AA = data; 
s = [0;diff(AA)];
ss = sign(s); 
ss(AA<0.4)=-1; 
ss= ss'; 
c = conv2(ss,win , 'valid');
win = ones(1,10)*-1; 
p = find(conv2(ss, win, 'valid') == -1);

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Ameer Hamza 2020-5-1

Can you share the data? I there a single window or several windows between 0.2 and 0.4?

nlm 2020-5-2

data.mat

Thanks Ameer for taking it up. Please find the data attached.

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Answer 1

Ameer Hamza 2020-5-2

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编辑：Ameer Hamza 2020-5-2

在 MATLAB Online 中打开

This shows the window of days in which the the value is within the specified range

data = load('data.mat');
AA = data.AA;
mask = (0.2 < AA) & (AA < 0.4);
days = find(mask); % contain the days on which the data is in range
plot(mask)
ylim([-0.2 1.2])

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nlm 2020-5-4

Thanks!

But this code also considers an increasing trend. What it selected are values which increased from 0.4 to 0.2 and then increased from 0.2 to 0.4. However, I'm looking for all the values where its only shows an decrease from 0.4 to 0.2, and it need not be monotonically decreasing, there can be some increases but it can to be below 0.4.