couples-class | R Documentation |
A class for spatial points and the corresponding temporal lags to be analyzed in order to test some covariance properties and some well known classes of space-time covariance functions models \loadmathjax
couples(
sel.staz,
sp.couples.in,
t.couples.in,
typetest = "sym",
typecode = numeric()
)
## S4 method for signature 'couples'
show(object)
## S4 method for signature 'couples'
x[i, by.row = FALSE, drop = FALSE]
## S4 method for signature 'couples'
summary(object)
sel.staz |
vector, the sequence of ID codes which denote the spatial points to be analyzed |
sp.couples.in |
two-column matrix: rows corresponding to the couples
of different spatial points, chosen among the ones fixed in |
t.couples.in |
vector of only positive (negative) temporal lags to be
analyzed. The corresponding negative (positive) temporal lags are included
authomatically for |
typetest |
character, set |
typecode |
type of object, i.e. numeric() or character(), specifies the
type of codification of the spatial points in the |
object |
object of class |
x |
object of class |
i |
index specifying rows or columns of the slot |
by.row |
logical, if |
drop |
logical, the argument is set, by default, equal to |
It is important to point out that:
both positive and negative temporal lags are automatically considered in
the slot @couples.st
and @tl.couples
for symmetry test
(typetest = "sym"
), separability test (typetest = "sep"
) and
type of non separability tests
(typetest = "tnSep"
). If the symmetry hyphotesis has not been rejected, only
positive temporal lags might be considered for the test on separability and type
of non separability (typetest = "sep"
and typetest = "tnSep"
), hence the
specific setzero
method must be used to set the negative temporal
lags equal to zero
for typetest = "tnSep"
the temporal lags should be chosen according to
the results of the sample non separability ratios, plotted through a boxplot
classified for temporal lags (see sepindex for more details)
for model tests (typetest
equal to "productSum"
,
"intProduct"
and "gneiting"
), the number of analyzed spatial
points must be used to create at least 3 spatial couples or multiple of 3,
such that each triplet satisfies the condition
\mjdeqn||\mathbfh_1||^2\gamma - ||\mathbfh_2||^2\gamma = ||\mathbfh_2||^2\gamma-||\mathbfh_3||^2\gamma||h_1||^2\gamma - ||h_2||^2\gamma = ||h_2||^2\gamma - ||h_3||^2\gamma
where \mjeqn\gamma \in ]0,1]\gamma \in ]0,1] only for typetest = "intProduct"
and "gneiting"
.
The number of positive temporal lags must be at least 3, or multiple
of 3, too. The condition \mjdeqnu_1^2\alpha-u_2^2\alpha=u_2^2\alpha-u_3^2\alphau_1^2\alpha - u_2^2\alpha = u_2^2\alpha - u_3^2\alpha
where \mjeqn\alpha \in ]0,1]\alpha \in ]0,1] must be satisfied for each triplet
(only for typetest = "intProduct"
and "gneiting"
), as clarified
in Cappello et al., 2018. The values of \mjeqn\gamma\gamma and \mjeqn\alpha\alpha are usually fixed
equal to 0.5 or 1 according that the behavior near the origin of the spatial
and temporal marginal covariograms is linear or quadratic, respectively.
Note that for each spatial triplet and each temporal triplet, 6 contrasts can
be defined. However, for typetest = "intProduct"
(test on the integrated
model) the user has to set arbitrarily one temporal lag equal to zero for each
spatial triplet in order to delete redundant contrasts, through the specific
setzero
method
couples.st
matrix, in which the first two columns contain the couples of spatial points (denoted with order numbers) to be analyzed and the other columns the temporal lags associated with each spatial couples
sel.staz
numeric or character, contains the ID codes of the selected spatial points
sp.couples
data.frame, contains the couples of order numbers associated with the spatial points to be analyzed and the couples of the ID codes
tl.couples
numeric, contains the temporal lags associated to the couples of the selected spatial points
typetest
character; contains the code of the test to be performed
Errors occur if
some spatial points, given in the sequence at the beginning of the function, have not been used to generate the couples of spatial points
there is at least one spatial couple with no specification of temporal lags
no temporal lags have been specified
the number of spatial points fixed in sel.staz
is less than 2
the construction of the sp.couples.in
is not consistent with the
test to be performed
Cappello, C., De Iaco, S., Posa, D., 2020, covatest: An R Package for Selecting a Class of Space-Time Covariance Functions. Journal of Statistical Software, 94(1) 1–42.
setzero
sel.staz.sym <- c("DERP016", "DENW065", "DEHE051", "DETH026", "DENW063", "DENI019",
"DENW068", "DEHE046", "DEUB029", "DEBY047", "DETH061", "DESN049")
sp.couples.in.sym <- matrix(data = c("DERP016", "DENW065", "DEHE051", "DETH026",
"DENW063", "DENI019", "DENW068", "DEHE046", "DEUB029", "DEBY047", "DETH061", "DESN049"),
ncol = 2, byrow = TRUE)
t.couples.in.sym <- c(1, 2)
couples.sym <- couples(sel.staz = sel.staz.sym, sp.couples.in = sp.couples.in.sym,
t.couples.in = t.couples.in.sym, typetest = "sym", typecode = character())
### methods for couples
#1. show
couples.sym
#2. [ extract
couples.sym[3, by.row = FALSE]
couples.sym[3, by.row = TRUE]
#3. summary
summary(couples.sym)
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