From the gslib book, I understand that there is a lag, and a lag
tolerance, and a cutoff. lag 0 is 0, the lag 1 is <0,tol], lag 2
, lag3 , etc. This allows for
overlap in the lags, if tolerance is larger than half the difference
between lags.
gstat uses regular lag (the first one is not shor
Dear sir,
I spent lot of time to figured it out what causing the difference in result of
R/gstat and gslib but didn't get any logical explanation. In my opinion the
source of difference is the cutoff and width.
I would be thankful if you give me the in depth explanation of these two
parameters
PUJAN RAJ REGMI wrote:
Dear sir,
Ya, Now I am comparing the results from gslib and R/gsat. The shape of
variograms exactly overlaps but the position of points varies, I don't
know why? or it is normal! I first checked the result of
omnidirectional variogram but still to have checked for direc
Dear sir,
Ya, Now I am comparing the results from gslib and R/gsat. The shape of
variograms exactly overlaps but the position of points varies, I don't know
why? or it is normal! I first checked the result of omnidirectional variogram
but still to have checked for directional cases. I hope the
Hi Edzer,
Well, I wrote similar because I don't now the details by heart.
Furthermore the we analysed the same data independently in R/gstat and
variowin/gslib. The emphasis of our comparisons was rather on what was
the most userfriendly workflow. So the question was not realy if gslib
yields exac
This would be my way, with kernel smoothing from spatstat function smooth.ppp:
Let's say that "cosa" is a dataframe with three columns x, y and z .
library(rgl)
library(ecespa) # for function "haz.ppp"; it requires (and load) spatstat
cosa.ppp <- haz.ppp (cosa) # makes ppp object
"easily".
ONKELINX, Thierry wrote:
Dear Pujan,
The helpfile (?variogram) is a wonderfull thing because it answers you
question about dist. It reads:
dist the average distance of all point pairs considered for this
estimate
I think that gstat is based on gslib (Edzer, please correct me if I'm
Hi all,
Does anyone know if there exists a function in R that can calculate
geographical slope and aspect (i.e. like elevational slope/aspect) on
grid values?
I've looked around on the R-sites but could not find anything on this.
I hope can help a simple soul...
Cheers, Roel
Roel May
Norwegia
Dear Erik,
In my opinion you beter first create an interpolated grid (e.g. with
kriging). Then plot this interpolated grid. That will reduce the number
of points dramatically. A 100 by 100 grid will probably do.
HTH,
Thierry
-
Michal,
thanks for the suggestions. If I try the wireframe I get a warning
message
"Warning message:
In nx * ny : NAs produced by integer overflow"
I haven't been able to figure out why that is, but could have something
to do with the 2.5mil * 2.5mil number of rows
My data are not in a grid
Dear Pujan,
The helpfile (?variogram) is a wonderfull thing because it answers you
question about dist. It reads:
dist the average distance of all point pairs considered for this
estimate
I think that gstat is based on gslib (Edzer, please correct me if I'm
wrong). Last year we com
Dear Thierry,
Thank you very much. Ya it worked after waiting for so long time. But i am bit
confused with the result! as my data set have 12m interval
both x and y direction but the result confused me. Please have a look at:
A<-read.table(file.choose(new=FALSE), sep = "",skip=8,header=FALSE)
n
Dear Pujan,
Calculating variograms on large datasets is computationally rather
heavy. So maybe R didn't hang but was still busy calculating the
variogram. Run your script overnight (or over the weekend) and see the
next morning if it finished.
I couldn't find an error in your code at first glance.
On May 7 2008, Meesters, Erik wrote:
Dear list members,
I'm looking for a function in R like the function r.in.xyz in GRASS (vs.
6.2). I have x, y, z data frame (UTM) with z equals depth and would like
to make a 3dperspective plot with rgl. My dataframe has 2.5 milion rows,
so I think it's neces
Dear list,
I am trying to plot semivariogram suing gstat packages. But as soon as i run
the command variogram the programs hangs!! I don't know what happened! Actually
in my data set i have many rows (96000). My data has 5 columns out of these
first 2 are x and y coordinates and the rest 3 are t
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