Re: setting regions for drawing polygons

[Glenn Carver <Glenn.Carver@xxxxxxxxxxxxxxxx>]

Ansley,

Thanks for your email. In fact I haven't quite solved my problem yet. I understand your comment about the Z axis. It would be nice if polymark used an 'abstract' axis because with some 4D data (xyzt) data I have I need to specify a region in all axes.

> 
> By the way, before you answered your own question, I thought you were
> talking about restricting the range of lat and lon

Yes, I was. And I'm still having problems. Basically what I think is happening is that if I try to specify a region for longitude (e.g. set reg/x=0:360), it's intefering with my lon coordinate array. I have lon[i=1:2562] and by setting the x=0:360, it seems that polymark only takes the first 360 points from lon. I can see this by cancelling the region for x and then all the points are plotted. I can set a region for latitude (y) fine, because my data does not use a latitude axis. The i axis is not really longitude but a count of the no. of data points I have.

what I want to do is plot a basemap for a specified region x=180:360,y=-40:40 and only plot the station points within that region (which is why I don't need the masking because my basemap needs to cover the same region).

Somehow I need to set a region to plot a basemap but then tell ferret to use all the station points and only plot the points that lie in the lat/lon region I've set. I was thinking I need an abstract axis that I can put my longitude points on so that ferret doesn't subset it but I've not figured out how to do that yet!

Hope that makes sense!

Regards,
              GLenn


> -- just while we're on the
> topic, they could be restricted by setting a mask for sigma:
> 
>    LET/BAD=999 sigma_restricted = IF(lon GE 200 AND lon LE 250 AND lat GE 0) THEN zpts ELSE 999
>    GO polymark  POLY  lon, lat, sigma_restricted
> 
> Ansley
> 
> 
> Glenn Carver wrote:
> 
> > Nothing like answering your own question.  8-)
> >
> > I neglected to mention that sigma is actually sigma[i=1:2562,k=1:40,l=1:400].
> >
> > If I set the region for k by set reg/k=1 and then call polymark, it doesn't work.
> >
> > Instead if I don't specify a region for k and then do:
> >   polymark poly/key lon lat sigma[k=1] circle
> >
> > it works!  Quite what difference specifying the region this way makes I don't understand.
> >
> >  Glenn
> >
> > On 2002.02.07 16:28 Glenn Carver wrote:
> > >
> > > Is it possible to use a region with the polymark script (or just the polygon command)?
> > >
> > > I have a dataset which has three arrays, lon[i=1:2562], lat[i=1:2562] and a value to be plotted at those coords, sigma[i=1:2562]. I want to plot a marker at each (lon,lat) point coloured according to the values in sigma. Polymark.jnl does the job fine for the full lat & long range. But I can't get it or polygon to work if I only want to plot markers over a region.
> > >
> > > Unfortunately, although the sequence of points is ordered in some manner I can't simply select a subset of the data. Ideally what I need to do is use set region/x=200:250/y=-30:0 but this doesn't work. I get an error that the number of polygons does not match the data.
> > >
> > > Is there a way around this?
> > >
> > > Thanks
> > >            Glenn
> > >
> > >
> > > --
> > >
> > > Dr. Glenn Carver, Centre for Atmospheric Science, Univ. of Cambridge,
> > > Chemistry Dept., Lensfield Road, Cambridge, CB2 1EW, UK.
> > >
> > > mailto:Glenn.Carver@atm.ch.cam.ac.uk  http://www.atm.ch.cam.ac.uk/~glenn/
> > > Phone: +44 (1223) 763827      ** please note new numbers **
> > > Fax:   +44 (1223) 763823
> > >
> > >
> > --
> >
> > Dr. Glenn Carver, Centre for Atmospheric Science, Univ. of Cambridge,
> > Chemistry Dept., Lensfield Road, Cambridge, CB2 1EW, UK.
> >
> > mailto:Glenn.Carver@atm.ch.cam.ac.uk  http://www.atm.ch.cam.ac.uk/~glenn/
> > Phone: +44 (1223) 763827      ** please note new numbers **
> > Fax:   +44 (1223) 763823
> 
> --
> Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246
> 
> 
> 
-- 

Dr. Glenn Carver, Centre for Atmospheric Science, Univ. of Cambridge,
Chemistry Dept., Lensfield Road, Cambridge, CB2 1EW, UK.

mailto:Glenn.Carver@atm.ch.cam.ac.uk  http://www.atm.ch.cam.ac.uk/~glenn/
Phone: +44 (1223) 763827      ** please note new numbers **
Fax:   +44 (1223) 763823