densitymap {GeoXp}R Documentation

Kernel density estimates and map

Description

The function densitymap draws kernel density estimates of the variable var with 'bkde.R' and a map with sites of coordinate (long,lat). Each site is associated to a value of var and there is interactivity between the two windows.

Usage

densitymap(long, lat, var, kernel='triweight',listvar=NULL, listnomvar=NULL,
carte=NULL, criteria=NULL,label="",cex.lab=1, pch=16, col="blue", xlab="",
ylab="", axes=FALSE, lablong="", lablat="")

Arguments

long a vector x of size n
lat a vector y of size n
var a vector of numeric values of size n
kernel Smoothing kernel (see help(bkde) for list of options)
listvar matrix of variables which permit to plot bubbles on map or add a graphic using the tk window
listnomvar a list with names of variables listvar
carte matrix with 2 columns for drawing spatial polygonal contours : x and y coordinates of the vertices of the polygon
criteria a vector of size n of boolean which permit to represent preselected sites with a cross, using the tcltk window
label vector of character of size n with names of sites
cex.lab character size of label on map
pch 16 by default, symbol for selected points
col "blue" by default, color of the density curve
xlab a title for the graphic x-axis
ylab a title for the graphic y-axis
axes a boolean with TRUE for drawing axes on the map
lablong name of the x-axis that will be printed on the map
lablat name of the y-axis that will be printed on the map

Details

The user can choose an interval on the density curve by mouse clicking on the graph on the extremities of interval or by specifying directly values. The sites selected by an interval are then represented on the map in red. The selection of sites on the map by `points' or `polygon' results in the drawing of the kernel densities of the subdistributions corresponding to this subset of sites. Finally, the user can modify the bandwith parameter with a cursor in the tcltk window (parameter alpha). alpha is the smoothing parameter for the kernel smooth : it represents the mean percentage of sample points involved in the local averaging (example : alpha=20 means that on average, n x 0.2 points are in any interval of length 2h where h is the usual bandwidth).

Value

A vector of boolean of size n. TRUE if the site was in the last selection.

Author(s)

Thomas-Agnan C., Aragon Y., Ruiz-Gazen A., Laurent T., Robidou L.

References

Aragon Yves, Perrin Olivier, Ruiz-Gazen Anne, Thomas-Agnan Christine (2009), Statistique et Econométrie pour données géoréférencées : modèles et études de cas

Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. New York: Springer.

Wand M.P. et Jones M.C. (1995), Kernel Smoothing, Chapman & Hall.

See Also

histomap, histobarmap, scattermap, densitymap

Examples

# data on price indices of real estate in France
data(immob)
midiP <- readShapePoly(system.file("shapes/region.shp", package="GeoXp")[1])
cont_midiP<-spdf2list(midiP)$poly
densitymap(immob$longitude,immob$latitude,immob$prix.vente,
carte=cont_midiP,listvar=immob,listnomvar=names(immob),
xlab="Prix de vente moyen par m2",label=immob$Nom,cex.lab=0.7,col='purple',pch=15)

# data olcol
example(columbus)
coords <- coordinates(columbus)
cont<-spdf2list(columbus)$poly

densitymap(coords[,1], coords[,2],columbus@data$CRIME,listvar=columbus@data,
carte=cont, listnomvar=names(columbus@data),
criteria=(columbus@data$CRIME>mean(columbus@data$CRIME)))

# data eire
data(eire)
eire.contours<-polylist2list(eire.polys.utm)
densitymap(eire.coords.utm$V1,eire.coords.utm$V2,eire.df$A,
carte=eire.contours,listvar=eire.df,listnomvar=names(eire.df),
xlab="Taux d'individus au groupe sanguin A",ylab="densite")


[Package GeoXp version 1.4 Index]