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Topic: How to extract data points from a plot (can't use 'ginput')
Replies: 6   Last Post: Jan 31, 2013 5:26 AM

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Steven Lord

Posts: 17,944
Registered: 12/7/04
Re: How to extract data points from a plot (can't use 'ginput')
Posted: Aug 25, 2008 11:12 AM
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"Forrest " <Remove.this@yahoo.com> wrote in message
news:g8uhe3$go8$1@fred.mathworks.com...
> "Steven Lord" <slord@mathworks.com> wrote in message
> <g8ug33$u1$1@fred.mathworks.com>...

>>
>> "Forrest " <Remove.this@yahoo.com> wrote in message
>> news:g8uf2j$j5s$1@fred.mathworks.com...

>> > I'm using the 'psd' function to take the power spectral
>> > density of a waveform. Afterwards I can view the plot

> of
>> > the psd, however, I can't seem to find the data that is
>> > being plotted from the psd. I have the plot, but I

> can't
>> > find the x and y coordinates. I can't use ginput
> because
>> > there are 5000 data points.
>>
>> Get a handle to the line that PSD plotted using

> FINDOBJ. Once you have that
>> handle, GET the XData and YData properties.
>>
>> --
>> Steve Lord
>> slord@mathworks.com
>>
>>

> Steve,
>
> I'm not very familiar with 'findobj'. Can you walk me
> through how to do this.


The first example from DOC FINDOBJ should do it, as long as the line created
by PSD is the only line on the current axes:

h = findobj(gca,'Type','line')

If it isn't, you'll need to specify another property that distinguishes the
PSD-created lines from the others. Take a look at the other documentation
examples for ideas of some of the properties you can use for that purpose.

--
Steve Lord
slord@mathworks.com





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