dbmss (version 1.2.4)

D.r: Estimation of the D function

Description

Estimates the D function

Usage

D.r(X, r, Cases, Controls, Intertype = FALSE)

Arguments

X

A point pattern (ppp.object), marks must be a dataframe with two columns: PointType: labels, as factors. PointWeight: weights.

r

A vector of distances.

Cases

One of the point types.

Controls

One of the point types.

Intertype

Logical; if TRUE, D is computed as Di in Marcon and Puech (2012).

Value

• A vector containing D(r) values.

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).

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 (2012). A typology of distance-based measures of spatial concentration. HAL SHS. 00679993.

See Also

K.r, DEnvelope, Kest, Kcross

Examples

data(paracou16)
plot(paracou16)

# Calculate D
r <- 0:30
ActualValues.X <- D.r(paracou16, r, "V. Americana", "Q. Rosea", Intertype = TRUE)

# Plot
PlotResults(r, DivideByPiR2(ActualValues.X, r), , ylab="D / (pi R^2)", ReferenceValue=0)