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Asked by Deniz on 10 Nov 2013

Hi,

I have a curve figure. How can i get the y-data (vector) for given x=linspace(0,R,c) out of figure?

Thanks

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Answer by Walter Roberson on 11 Nov 2013

Accepted answer

xd = get(get(gca,'children'),'xdata'); % return the plot data yd = get(get(gca,'children'),'ydata'); x = 1 : 0.1 : 3; %places to sample at y = interp1(xd, yd, x); %interpolate from stored data at locations to be sampled

Answer by dpb on 10 Nov 2013

x = get(get(gca,'children'),'xdata'); % return the plot data y = get(get(gca,'children'),'ydata'); y=y(x(x==linspace(0,R,c)));

Trivial example from keyboard to illustrate...

>> plot(rand(1,3)) >> xdat=get(get(gca,'children'),'xdata'); >> ydat=get(get(gca,'children'),'ydata'); >> xvec=linspace(0,1,2); >> y=ydat(ismember(xdat,xvec)) y = 0.8147 >>

You'll get some other value depending on state of rng at the time but the process should be clear to retrieve the data from the plot and find a location.

NB that if your x values are non-integer values you may need to make the comparison "fuzzy" rather than exact as is shown here.

Answer by Deniz on 10 Nov 2013

this solution doesn't work for me.

plot(rand(1,3))

xdat=get(get(gca,'children'),'xdata')

ydat=get(get(gca,'children'),'ydata')

xvec=linspace(1,3,0.1)

y=ydat(ismember(xdat,xvec))

what i get:

xdat =

1 2 3

ydat =

0.0462 0.0971 0.8235

xvec =

Empty matrix: 1-by-0

y =

Empty matrix: 1-by-0

I need the y-vector for a x-vektor:xvec=linspace(1,3,0.1)

Any other ideas?

Thanks

Walter Roberson on 11 Nov 2013

The last argument to linspace() needs to be a count, not an increment. Use ":" if you want an increment

1 : 0.1 : 3

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