Description Usage Arguments Details Value Author(s) References Examples
Creates a standard covariance model (cmodStd
)
object for geostatistical data.
1 2 3 4 5 6 7 8 9 10 11 12 13 |
model |
A covariance model (e.g.,
|
psill |
The partial sill of the model. Must be a positive number. |
r |
The range parameter |
evar |
The variance of the errors. Must be non-negative number. The default is 0. |
fvar |
The finescale variance (microscale error). Must be a non-negative number. The default is 0. |
par3 |
The value of the third parameter for 3 parameter models. Must be a positive number. The default is 0.5. |
longlat |
A logical value indicating whether great
circle distance should be used. The default is
|
angle |
The major axis of geometric anisotropy (the
direction of strongest spatial dependence). Must be
between [0, 180) if |
ratio |
The ratio of the minor axis range over the major axis range. The value must be between (0, 1]. |
radians |
A logical value indicating whether the
angles returned should be in degrees or radians. The
default is |
invert |
A logical value indicating whether the axes
of the coordinates should be inverted (i.e., the x- and
y-axis are switched). The default is |
The general, isotropic form of the specified covariance function is
psill
* ρ(d
; r
) +
(evar
+ fvar
) * (d == 0
), where
ρ is the correlation function of the parametric
models and d
is the distance between the
relevant coordinates.
For the exponential
model, ρ(d
;
r
) is exp(-d
/r
).
For the gaussian
model, ρ(d
;
r
) is exp(-d^2
/r^2
).
For the matern
model, ρ(d
;
r
) is
2^(1-par3
)/gamma
(par3
)*sd
^par3
*besselK(sd,
nu = par3)
, where sd = d/r
.
For the amatern
(alternative Matern) model,
ρ(d
; r
) is
2^(1-par3)/gamma(par3)*sd^par3*besselK(sd, nu =
par3)
, where sd = 2 * sqrt(par3) * d/r
.
For the spherical
model, ρ(d
;
r
) is 1 - 1.5*sd + 0.5*(sd)^3
if d <
r
, and 0 otherwise, with sd = d/r
.
For the wendland1
model, ρ(d
;
r
) is (1 - sd)^4 * (4*sd + 1)
if d <
r
, and 0 otherwise, with sd = d/r
.
For the wendland2
model, ρ(d
;
r
) is (1 - sd)^6 * (35*sd^2 + 18*sd + 3))/3
if d < r
, and 0 otherwise, with sd = d/r
.
For the wu1
model, ρ(d
; r
)
is (1 - sd)^3 * (1 + 3*sd + sd^2)
if d < r
,
and 0 otherwise, with sd = d/r
.
For the wu2
model, ρ(d
; r
)
is (1 - sd)^4*(4 + 16*sd + 12*sd^2 + 3*sd^3))/4
if
d < r
, and 0 otherwise, with sd = d/r
.
For the wu3
model, ρ(d
; r
)
is (1 - sd)^6 * (1 + 6*sd + 41/3*sd^2 + 12*sd^3 +
5*sd^4 + 5/6*sd^5)
if d < r
, and 0 otherwise,
with sd = d/r
.
Returns a cmodStd
object.
Joshua French
Waller, L. A., & Gotway, C. A. (2004). Applied Spatial Statistics for Public Health Data. John Wiley & Sons.
1 | cmod_std(model = "exponential", psill = 1, r = 1)
|
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