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Make TV a function of X? [message #18480] Thu, 06 January 2000 00:00 Go to next message
raouldukey is currently offline  raouldukey
Messages: 15
Registered: November 1999
Junior Member
Hi all! Thanks for all the helpful tips I have been
picking up by lurking around here.

I have a data set that is irregularly sampled, and I
need to make an image-type plot of this data, and was
hoping to get some suggestions on the best way to do this.

The first record of my data set is the time of the sample.
The experiment is started, and say 100 samples are taken...
one every 5 seconds. Then nothing was taken for 1 hour
and then a sample every 10 seconds was made for the next
5 hours. I want to take this sort of data set and make
an image plot with the time of the samples for the x axis.
Is there an easy way to do this and have the time axis
actually mean anything? Usually, you are just defining
the time range for the axis labels.

The obvious way that comes to my mind is to just make
a uniform time scale, and then resample the data to fit
this scale, filling in the rows and rows of zeros where
necessary. The times on my real data set fluctuate quite
a bit more than the example I gave. Is this the best
(only?) way to do this sort of thing? Any advice is
appreciated.

BTW, I am using Craig Markwardt's plotimage.pro proceedure,
to do my image plots, and I recommend it highly!

Cheers!


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Re: Make TV a function of X? [message #18572 is a reply to message #18480] Wed, 12 January 2000 00:00 Go to previous message
robert.m.candey.1[2] is currently offline  robert.m.candey.1[2]
Messages: 11
Registered: May 1999
Junior Member
In article <854pqn$lpa$1@nnrp1.deja.com>, raouldukey@my-deja.com wrote:

> . . .
> I am thinking I will have to make some sort of fake data set by
> making a fake time array and put the data in where it exists, and
> fill it with zeros where it doesn't. Yuck! This has to be
> a common problem, so has anyone else thought of a solution?
>
> Cheers

I missed your first post since the news server I use was down for a week
and I probably don't understand what you need to do. On the off chance
that it helps, check out
<ftp://nssdc.gsfc.nasa.gov/CDAWlib/source/spectrogram.pro> as it will
plot a 2-dim spectrogram with varying x and y values.

(You may need align_center.pro (replace "exp" with "10^") and
Colorbar.pro). There are some radar routines also.

--
Robert.M.Candey@gsfc.nasa.gov 1-301-286-6707 (286-1771 fax)
NASA Goddard Space Flight Center, Code 632
Greenbelt MD 20771 USA <http://nssdc.gsfc.nasa.gov/personnel/rcandey/>
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