MATLAB: Find peaks of a vector contains nan values

Question

b=[ NaN NaN NaN NaN 0.0691 0.0697 0.0760 0.0829 0.0891 0.0907 0.0952 0.0941 0.0964 0.0963 0.1003 0.0913 0.0775 0.0725 0.0799 0.0843 0.0677 0.0449 0.0280 0.0212 0.0184 0.0163 0.0143 0.0123 0.0087]

[~,lct] = findpeaks(b,'MinPeakheight',0.05,'MinPeakDistance',1);

after running this statement

i am getting warning and my lct is

lct = 1×0 empty double row vector

it contains nothing. and warning is

Warning: Invalid MinPeakHeight. There are no data points greater than

MinPeakHeight.

> In findpeaks>removePeaksBelowMinPeakHeight (line 516)

In findpeaks (line 147)

can you please solve my problem. thanking you sir

Answer 1

The code in your orginial question differs from the code you provided in the comments under your question. In your original code, input values were all positive. In your second version of code, input values were negative an you used different MinPeakHeight values.

Initial version

This is the code exactly copied form your question. I added the figure. Note that 'b' and 'MinPeakHeight' are positive.

b=[ NaN       NaN       NaN       NaN    0.0691    0.0697    0.0760    0.0829    0.0891    0.0907    0.0952    0.0941    0.0964    0.0963   0.1003    0.0913    0.0775    0.0725    0.0799    0.0843    0.0677  0.0449    0.0280    0.0212    0.0184    0.0163    0.0143    0.0123   0.0087]
[~,lct] = findpeaks(b,'MinPeakheight',0.05,'MinPeakDistance',1);
% figure

figure
plot(b, '-b')
hold on
plot(lct, b(lct), 'm*') %labelpeaks

Incorrect version

This is the code exactly copied from your comment where the sign of 'b' and 'MinPeakHeight' are negative.

b=[ NaN       NaN       NaN       NaN    0.0691    0.0697    0.0760    0.0829    0.0891    0.0907    0.0952    0.0941    0.0964    0.0963   0.1003    0.0913    0.0775    0.0725    0.0799    0.0843    0.0677  0.0449    0.0280    0.0212    0.0184    0.0163    0.0143    0.0123   0.0087]
[~,lct] = findpeaks(-b,'MinPeakHeight',-0.0605,'MinPeakDistance',1);
% figure
figure
plot(-b, 'b-')

It produces a warning message:

Warning: Invalid MinPeakHeight. There are no data points greater than MinPeakHeight.

If you look at the plot of -b below, there are no peaks that are above -0.06 which is where you've set the threshold for the minimum peak height (horizontal reference line).

For more info on MinPeakHeighthttps://www.mathworks.com/help/signal/ref/findpeaks.html#bufbbs1-MinPeakHeight