Create multi slopes from a profile

Hello there,

Is there a possible way to create some slopes within a profile? My case: I have a profile containing some group of values separated by nans. My intention is how to create slopes for each group. So, since there are some groups in the profile, there will be some slopes which corresponds to each group.

Please find attached mat file for the data.

Cheers

Answer 1

[Star Strider]

I am not certain what you want. This code performs a linear regression on the line clusters and then plots it for each of them.

Try this —

load('profiles_z_d.mat')
whos('-file', 'profiles_z_d.mat')

  Name      Size             Bytes  Class     Attributes

  d_x1      1x883             7064  double              
  z         1x883             7064  double              

Q = [nnz(isnan(d_x1)) nnz(isnan(z))];

idx = ~isnan(d_x1);
startidx = strfind(idx, [0 1])+1;
stopidx = strfind(idx, [1 0]);
ssidx = [startidx;  stopidx];

for k = 1:size(ssidx,2)
    G{k,1} = d_x1(ssidx(1,k):ssidx(2,k));
    G{k,2} = z(ssidx(1,k):ssidx(2,k));
    B(:,k) = [G{k,1}; ones(size(G{k,1}))].' \ G{k,2}.';
end

% B

figure
plot(d_x1, z)
hold on
for k = 1:size(B,2)
    rline = [G{k,1}; ones(size(G{k,1}))].' * B(:,k);
    plot(G{k,1}, rline, '-r')
    text(max(G{k,1})+0.1, max(rline), sprintf('y = %.2f \\cdotx% +.2f',B(:,k)), 'Horiz','left')
end
hold off
xlim([0 20])
title('All Data')

figure
plot(d_x1, z)
hold on
for k = 1:size(B,2)
    rline = [G{k,1}; ones(size(G{k,1}))].' * B(:,k);
    plot(G{k,1}, rline, '-r')
    text(max(G{k,1})+0.1, max(rline), sprintf('y=%.2f\\cdotx%+.2f',B(:,k)), 'Horiz','left')
end
hold off
title('Selected Detail')
xlim([0 5])
ylim([390 415])

.

[Adi Purwandana]

Bravo, that's exactly what I want. Thank you very much!

[Star Strider]

As always, my pleasure!