Extract data from nyquist plot

6 views (last 30 days)
Hello,
I am trying to extract the data of a nyquist plot and plot it into another figure (I have to do this for another API normally using nyquist would be ok for me).
If i try to plot the data again I get some strange behaviour compared to the original nyquist() plot. Anybody got an idea how to figure this out?
On the left is the nyquist plot created by matlab in
nyquist(G);
and on the right I replot the extracted data
plot(squeeze(re),squeeze(im));
Used lightweight example:
clear all;
close all;
G = tf([1],[1 0.5]);%observerd transfer funciton
G.OutputDelay = 8;
[MAG,PHASE,W] = bode(G);
figure %do "normal" nyquist plot and extract real and imaginary data
[re,im] = nyquist(G);%extract real and imaginary part
nyquist(G);
figure% do own nyquist plot with extracted data
plot(squeeze(re),squeeze(im));
Thanks for you help!

Accepted Answer

Ameer Hamza
Ameer Hamza on 15 Jun 2020
Edited: Ameer Hamza on 15 Jun 2020
This code shows how you can extract the data from the graphic handles
G = tf(1,[1 0.5]);%observerd transfer funciton
G.OutputDelay = 8;
fig = figure; %do "normal" nyquist plot and extract real and imaginary data
nyquist(G);
hg = findall(fig, 'Type', 'hggroup');
l = hg.Children;
xdata1 = l(1).XData;
ydata1 = l(1).YData;
xdata2 = l(2).XData;
ydata2 = l(2).YData;
figure% do own nyquist plot with extracted data
plot(xdata1, ydata1, xdata2, ydata2);
  3 Comments

Sign in to comment.

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by