How do I pick specific rows of a txt file and plot data?

Hi ! How can I choose specific lines with values from a txt file that contains both letters and numbers? For example in the attached file I want to delete the first 14 rows and make a spectra plot of the two columns.

Answer 1

[Star Strider]

Try this:

D1 = readmatrix('collagen405.txt', 'HeaderLines',14);
x = D1(:,1);
y = D1(:,2);

figure
plot(x, y)
grid
title('Spectrum Plot')
xlabel('Frequency')
ylabel('Amplitude')

Also consider:

figure
semilogy(x(y>0), y(y>0))
grid
title('Spectrum Plot')
xlabel('Frequency')
ylabel('Amplitude')

.