Dhat {dbmss} | R Documentation |
Estimation of the D function
Description
Estimates the D function
Usage
Dhat(X, r = NULL, Cases, Controls = NULL, Intertype = FALSE, CheckArguments = TRUE)
Arguments
X |
A weighted, marked, planar point pattern ( |
r |
A vector of distances. If |
Cases |
One of the point types. |
Controls |
One of the point types. If |
Intertype |
Logical; if |
CheckArguments |
Logical; if |
Details
The Di function allows comparing the structure of the cases to that of the controls around cases, that is to say the comparison is made around the same points. This has been advocated by Arbia et al. (2008) and formalized by Marcon and Puech (2012).
Value
An object of class fv
, see fv.object
, which can be plotted directly using plot.fv
.
Note
The computation of Dhat
relies on spatstat functions Kest
and Kcross
.
References
Arbia, G., Espa, G. and Quah, D. (2008). A class of spatial econometric methods in the empirical analysis of clusters of firms in the space. Empirical Economics 34(1): 81-103.
Diggle, P. J. and Chetwynd, A. G. (1991). Second-Order Analysis of Spatial Clustering for Inhomogeneous Populations. Biometrics 47(3): 1155-1163.
Marcon, E. and F. Puech (2017). A typology of distance-based measures of spatial concentration. Regional Science and Urban Economics. 62:56-67.
See Also
Examples
data(paracou16)
autoplot(paracou16)
# Calculate D
r <- 0:30
(Paracou <- Dhat(paracou16, r, "V. Americana", "Q. Rosea", Intertype = TRUE))
# Plot (after normalization by pi.r^2)
autoplot(Paracou, ./(pi*r^2) ~ r)