angleplotmap: Detection of an eventual directional trend

In tibo31/GeoXp: Interactive Exploratory Spatial Data Analysis

Detection of an eventual directional trend

Description

The function angleplotmap() is used to detect an eventual directional trend associated to variable name.var. It represents the absolute difference between the value of name.var at two sites as a function of the angle between vector \overrightarrow{s_is_j} and the x-axis.

Usage

angleplotmap(sf.obj, name.var, quantiles = TRUE, 
  criteria = NULL, carte = NULL, identify = NULL, cex.lab = 0.8, pch = 16, 
  col = "lightblue3", xlab = "angle", ylab = "absolute magnitude", axes = FALSE,
  lablong = "", lablat = "")

Arguments

sf.obj	object of class sf
name.var	a character; attribute name or column number in attribute table
quantiles	a boolean to represent the Additive Quantile Regression Smoothing
criteria	a vector of boolean which permit to represent preselected sites with a cross, using the tcltk window (must be equal to the number of spatial units)
carte	matrix with 2 columns for drawing spatial polygonal contours : x and y coordinates of the vertices of the polygon
identify	if not NULL, the name of the variable for identifying observations on the map
cex.lab	character size of label
pch	16 by default, symbol for selected points
col	"lightblue3" by default, color of bars on the cloud map
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

For each couple of sites (s_i,s_j), the graphic represents on the y-axis the absolute difference between var_i and var_j :

D_{ij}=|var_i-var_j|

and on the x-axis the angle \theta_{ij} between \overrightarrow{s_is_j} and the x-axis. Possibility to represent a smoothing spline regression quantile g_\alpha. For 0<\alpha<1,

Pr[D_{ij}<g_\alpha(\theta{ij})]=\alpha

If that case, only the pair of sites (s_i,s_j) verifying :

D_{ij}>g_{max(\alpha)}(\theta{ij})

are represented.

Value

In the case where user click on save results button, a matrix of integer is created as a global variable in last.select object. It corresponds to the numbers of spatial unit corresponding to couple of sites selected just before leaving the Tk window.

Author(s)

Thomas-Agnan Christine, Aragon Yves, Ruiz-Gazen Anne, Laurent Thibault, Robidou Lauriane

References

Thibault Laurent, Anne Ruiz-Gazen, Christine Thomas-Agnan (2012), GeoXp: An R Package for Exploratory Spatial Data Analysis. Journal of Statistical Software, 47(2), 1-23.

Roger S.Bivand, Edzer J.Pebesma, Virgilio Gomez-Rubio (2009), Applied Spatial Data Analysis with R, Springer.

See Also

variocloudmap, driftmap

Examples

######
# data Conflicts Africa
if (require(spData, quietly = TRUE)) {
 data(afcon, package = "spData")
}
# afcon is a data.frame object. We have to create
# a Spatial object, by using first the longitude and latitude
# to create Spatial Points object ...
require(sf)
afcon.sf <- st_as_sf(afcon, coords = c("x", "y"), crs = 4326)

# optional : we add some contours that don't correspond to the spatial unit
# but are nice for mapping
africa <- st_read(system.file("shapes/Africa.shp", package = "GeoXp")[1])

# A basic call of histomap function
angleplotmap(afcon.sf, "totcon", carte = africa,
  identify = "name", cex.lab = 0.6)
 
## Not run:  
if (require(sp, quietly = TRUE)) {
 data(meuse, package = "sp")
 meuse_sf <- sf::st_as_sf(meuse, coords = c("x", "y"), crs = 28992, agr = "constant")
 data(meuse.riv, package = "sp")
 meuse.sr <- sf::st_as_sf(SpatialPolygons(list(Polygons(list(Polygon(meuse.riv)), "meuse.riv"))),
     crs = 28992)
}

angleplotmap(meuse_sf, "copper", col = "green", quantiles = TRUE, 
  cex.lab = 0.7, xlab = "Concentration in plomb (in ppm)", pch = 7, 
  carte = meuse.sr)

## End(Not run)

tibo31/GeoXp documentation built on April 8, 2023, 7:50 a.m.