extracting 20% of the data from a table

i have the following data table that represents the curve that is is shown in the plot, at row number 9 in this table we have the peak point, th max point for the variable NE8, we would like to split our table in a way such that we extract 20% of the data points we have above the peak and 20% of the data below the peak and the peak point from that table? is there an easy way that would allow us to do that ?

thanks in advance

Answer 1

[KSSV]

T = readtable('https://in.mathworks.com/matlabcentral/answers/uploaded_files/1031740/testProfile.txt') ;
plot(T.NE,T.GDALT)

x = T.NE ; 
y = T.GDALT ; 
peak_y = T.GDALT(9) ; 
peak_x = T.NE(9) ; 

% idx = y <= peak_y ; 
idx = x <= peak_x ; 

plot(x,y,'r',x(idx),y(idx),'*g',x(~idx),y(~idx),'*k')
legend('Curve','below peak','above peak')

[Salma fathi]

Thank you, this was helpful.