[Gstat-info] variogram plot with a priori variance

[Edzer Pebesma]

I'll modify the source code such that the gstat::: is not needed 
anymore, and will document the panel function, and use your example 
there. Thanks!
--
Edzer

Paul Hiemstra wrote:
> Hi Giovanni,
>
> I'm happy that it works! Plotting a gstatVariogram object calls the 
> function plot.gstatVariogram. In turn that uses the panel function 
> vgm.panel.xyplot. This last panel function is normally not available 
> to the user, only through the gstat::: syntax. I found this by 
> browsing through the gstat-package source code. The variogram plot 
> function is documented under ?plot.gstatVariogram, for some other 
> things you need to go to the source code in order to find how it works.
>
> cheers,
> Paul
>
> G. Allegri wrote:
>> Thanks Paul, this works perfectly:
>>
>> plot(t0VARIO,VgmANIS_ZON,panel=function (x, y,...){
>> gstat:::vgm.panel.xyplot(x, y,...)
>> panel.abline(h=var(t0$EceZ))
>> })
>>
>> Having previously loaded the lattice library, needed to use 
>> panel.abline().
>> I suppose vgm.panel.xyplot is an overloaded method of xyplot, and that
>> calling plot() with a gstat object creates a "vgm.panel.xyplot" panel
>> as default. Is it right?
>> Where is this "low level" code documented?
>>
>> Cheers,
>> Giovanni
>>
>>
>>
>> 2008/3/9, Paul Hiemstra <p.hiemstra at geo.uu.nl>:
>>  
>>> Hi Giovanni,
>>>
>>>  You only get the line because that is what you specify in the panel
>>>  function. To also get the sample variogram and variogram model you 
>>> need
>>>  to start the panel function with a call to the original panel function
>>>  for the variogram (gstat:::vgm.panel.xyplot, don't forget the gstat:::
>>>  part) and then add the extra stuff. In general:
>>>
>>>  panel = function(x, y, ...){
>>>     original_panel_function(x, y, ...)
>>>     new_stuff
>>>  }
>>>
>>>  This is an example of a custom variogram panel function I use:
>>>
>>>  function (x, y, model, subscripts, ...)
>>>  {
>>>     gstat:::vgm.panel.xyplot(x, y, model = model, subscript = TRUE,
>>>         ...)
>>>     no_digits = function(a) {
>>>         if (a > 10)
>>>             return(0)
>>>         else {
>>>             if (a < 1)
>>>                 return(2)
>>>             else return(1)
>>>         }
>>>     }
>>>     nugget = sum(model[1, "psill"])
>>>     sill = sum(model[, "psill"])
>>>     range = sum(model[, "range"])
>>>     txt = paste("Model: ", as.character(model[2, "model"]), 
>>> "\nNugget: ",
>>>         round(nugget, digits = no_digits(nugget)), "\nSill: ",
>>>         round(sill, digits = no_digits(sill)), "\nRange: ", 
>>> round(range,
>>>             digits = no_digits(range)), sep = "")
>>>     ltext(max(x), 0.02 * max(y), txt, font = 2, cex = 0.7, adj = c(1,
>>>         0), col = grey(0.3))
>>>  }
>>>
>>>  cheers,
>>>  Paul
>>>
>>>
>>>
>>>
>>>  G. Allegri wrote:
>>>  > Sorry for the many posts I'm sending...
>>>  > I need to plot the a-priori variance on an anisotropic variogram 
>>> plot.
>>>  > I've tried using the panel argument, this way:
>>>  >
>>>  > 
>>> plot(t0VARIO,VgmANIS_ZON,panel=function(x,y){panel.abline(h=var(t0$EceZ))}) 
>>>
>>>  >
>>>  > where,
>>>  > t0VARIO is the ESV
>>>  > VgmANIS_ZON is an zonal anisotropic model (two directions)
>>>  >
>>>  > The problem is that, using the panel function the a-priori variance
>>>  > line is plotted on both the direction panels, but not the variograms
>>>  > and the model.
>>>  > Are there other ways to add graphics to variogram plots?
>>>  >
>>>  > Thanks again for precious support!
>>>  > Giovanni
>>>
>>>    
>>>> ------------------------------------------------------------------------ 
>>>>
>>>>       
>>>  >
>>>  > _______________________________________________
>>>  > Gstat-info mailing list
>>>  > Gstat-info at geo.uu.nl
>>>  > http://mailman.geo.uu.nl/mailman/listinfo/gstat-info
>>>  >
>>>
>>>
>>>
>>> -- 
>>>  Drs. Paul Hiemstra
>>>  Department of Physical Geography
>>>  Faculty of Geosciences
>>>  University of Utrecht
>>>  Heidelberglaan 2
>>>  P.O. Box 80.115
>>>  3508 TC Utrecht
>>>  Phone:  +31302535773
>>>  Fax:    +31302531145
>>>  http://intamap.geo.uu.nl/~paul
>>>
>>>
>>>     
> <
>