variogram.cloud(formula, data=<<see below>>, subset=<<see below>>, na.action=<<see below>>, azimuth=0, tol.azimuth=90, maxdist=<<see below>>, bandwidth=1e+307, FUN=function(zi, zj) (zi - zj)^2/2))
z ~ x + y
The
z
variable is a numeric response.
Variables
x
and
y
are the locations.
All variables in the formula must be vectors of equal length
with no missing values (
NA
s).
The formula may also contain expressions for the variables, e.g.
sqrt(count)
or
log(age+1)
.
The right hand side may also be a call to the
loc
function
e.g.
loc(x,y)
.
The
loc
function can be used to correct for geometric anisotropy,
see the
loc
help file.
formula
.
model.frame
after
any
subset
argument has been used.
The default (with
na.fail
) is to create an error
if any missing values are found.
A possible alternative is
na.omit
, which deletes observations
that contain one or more missing values.
tol.azimuth
will
be included in the output.
tol.azimuth
greater than or equal to 90 implies the of use all directions.
z[i]
,
z[j]
.
"vgram.cloud"
that inherits from
"data.frame"
.
The columns are:
FUN
for the
z[iindex]
,
z[jindex]
.
call
with an image of the call
that produced the object.
Methods for class
"vgram.cloud"
include
boxplot
,
plot
and
identify
.
If all directions and distances are included the return object will
have n*(n-1)/2 rows where n is the number of observations.
This can get very large, even for relatively small n.
The argument
maxdist
can be used to limit the size.
Typically values beyond half the maximum distance in the data
are not used in estimating the variogram function.
Cressie, Noel. (1993). Statistics For Spatial Data, Revised Edition. Wiley, New York.
v1 <- variogram.cloud(coal ~ x + y, data=coal.ash) plot(v1) boxplot(v1)