echelon: Echelon analysis for spatial data

In echelon: The Echelon Analysis and the Detection of Spatial Clusters using Echelon Scan Method

Echelon analysis for spatial data

Description

The echelon function divides the study area into structural entities, called 'echelons', based on neighbor information and draws a dendrogram.

Usage

echelon(x, nb, dendrogram = TRUE, name = NULL,
      main = NULL, ylab = NULL, yaxes = TRUE, ylim = NULL,
      xaxes = FALSE, xdper = c(0, 1), dmai = NULL,
      col = 1, lwd = 1, symbols = 4, cex.symbols = 1, col.symbols = 4,
      ens = TRUE, adj.ens = 1, cex.ens = 0.8, col.ens = 1,
      profiles = FALSE, nb.check = TRUE)

Arguments

x	A numeric vector containing data values.
nb	Neighbor information data: an object of class nb or a weights matrix.
name	Region names. if NULL, it is assigned seq_along(x).
dendrogram	Logical. if TRUE, draws an echelon dendrogram.
main	Related to dendrogram drawing. The main title for the dendrogram.
ylab	Related to dendrogram drawing. The title for the y-axis.
yaxes	Related to dendrogram drawing. Logical. if TRUE, draws the y-axis.
ylim	Related to dendrogram drawing. If not specified, the y-axis scale is set to c(min, max).
xaxes	Related to dendrogram drawing. Logical. if TRUE, draws the x-axis.
xdper	Related to dendrogram drawing. The percentage of the x-axis to display, specified in [0, 1].
dmai	Related to dendrogram drawing. A numeric vector of the form c(bottom, left, top, right) specifying margin sizes in inches. Default is c(0.4, 0.8, 0.3, 0.01).
col	Related to dendrogram drawing. The line color of the dendrogram.
lwd	Related to dendrogram drawing. The line width of the dendrogram.
symbols	Related to dendrogram drawing. An integer specifying a symbol or a single character. If integer, it corresponds to pch in par.
cex.symbols	Related to dendrogram drawing. A magnification factor for the plotting symbols.
col.symbols	Related to dendrogram drawing. The color for the plotting symbols.
ens	Related to dendrogram drawing. Logical. if TRUE, draw the labels of echelon numbers.
adj.ens	Related to dendrogram drawing. Adjusts the position of echelon number labels (see text for 'adj').
cex.ens	Related to dendrogram drawing. A magnification factor for the echelon number labels.
col.ens	Related to dendrogram drawing. The color for the echelon number labels.
profiles	Logical. If TRUE, returns the echelon profiles result (see [2] for details).
nb.check	Logical. if TRUE, checks for errors in the neighbor information data.

Value

The echelon function returns an object of class echelon, which contains the following components:

Table	A summary of each echelon.
Echelons	The regions that make up each echelon.

Note

Any NA values in x are replaced with the minimum value of x.

The functions Sf::st_read and spdep::poly2nb are helpful for creating the object specified in the nb argument.

Author(s)

Fumio Ishioka

References

[1] Myers, W.L., Patil, G.P. and Joly, K. (1997). Echelon approach to areas of concern in synoptic regional monitoring. Environmental and Ecological Statistics, 4, 131–152.

[2] Kurihara, K., Myers, W.L. and Patil, G.P. (2000) Echelon analysis of the relationship between population and land cover patter based on remote sensing data. Community ecology, 1, 103–122.

See Also

echepoi and echebin for cluster detection based on echelons.

Examples

##Echelon analysis for one-dimensional data with 25 regions
#A weights matrix
one.nb <- matrix(0,25,25)
one.nb[1,2] <- 1
for(i in 2:24) one.nb[i,c(i-1,i+1)] <- c(1,1)
one.nb[25,24] <- 1

#25 random values
one.dat <- runif(25) * 10

#Echelon analysis
echelon(x = one.dat, nb = one.nb)


##Echelon analysis for SIDS data for North Carolina
#Mortality rate per 1,000 live births from 1974 to 1984
library(spData)
data("nc.sids")
SIDS.cas <- nc.sids$SID74 + nc.sids$SID79
SIDS.pop <- nc.sids$BIR74 + nc.sids$BIR79
SIDS.rate <- SIDS.cas * 1000 / SIDS.pop

#Echelon analysis
SIDS.echelon <- echelon(x = SIDS.rate, nb = ncCR85.nb, name = row.names(nc.sids),
  symbols = 12, cex.symbols = 1.5, ens = FALSE)
text(SIDS.echelon$coord, labels = SIDS.echelon$regions.name,
  adj = -0.1, cex = 0.7)

#Echelon Profiles
echelon(x = SIDS.rate, nb = ncCR85.nb, profiles = TRUE)

echelon documentation built on April 3, 2025, 11:45 p.m.