Applied Spatial Statistics: Problem Set # 1

Fang Zhang

date()

## [1] "Wed Feb 12 11:27:13 2014"

Due Date: February 12, 2014

Total Points: 40

Use the Columbus, OH crime data from http://myweb.fsu.edu/jelsner/data/columbus.zip.

  1. Read the data into R and create a choropleth map of the CRIME variable using the spplot method.
  2. Compute Moran's I for the CRIME variable.
  3. Create a Moran's scatter plot using the CRIME variable. Label the axes and include the regression line.
  4. Check the value of Moran's I by determining the slope of the regression line.

1. Read the data into R and create a choropleth map of the CRIME variable using the spplot method.

open file

require(maptools) require(rgdal) download.file(“http://myweb.fsu.edu/jelsner/data/columbus.zip”, “columbus.zip”, mode = “wb”) unzip(“columbus.zip”) CC = readOGR(dsn = “.”, layer = “columbus”)

check data

slotNames(CC) str(CC, max.level=2) head(CC@data) df = CC@data

SSPLOT

plot(CC) spplot(CC, “CRIME”, pretty = TRUE) require(RColorBrewer) range(CC$CRIME) rng = seq(0, 70, 10) cls = brewer.pal(7, “Greens”) spplot(CC, “CRIME”, col.regions=cls, at=rng,sub = “Crime Data in Oho”)

2.Compute Moran's I for the CRIME variable.

BUILD NB

require(spdep) CC.nb = poly2nb(CC) CC.wts = nb2listw(CC.nb) ##CALCULATE MORAN'S I m = length(CC$CRIME) s = Szero(CC.wts) moran(CC$CRIME, CC.wts, n = m, S0 = s) ##TEST FOR WEIGHTING STYLE moran.test(CC$CRIME, nb2listw(CC.nb, style = “W”))$estimate[1] moran.test(CC$CRIME, nb2listw(CC.nb, style = “B”))$estimate[1] # binary moran.test(CC$CRIME, nb2listw(CC.nb, style = “S”))$estimate[1] # variance-stabilizing

3. Create a Moran's scatter plot using the CRIME variable. Label the axes and include the regression line.

require(ggplot2) Wsids = lag.listw(CC.wts, CC$CRIME) dat = data.frame(CC = CC$CRIME, Wsids = Wsids) ggplot(dat, aes(x = CC, y = Wsids)) + geom_point() + geom_smooth(method = “lm”) + xlab(“Columbus Crime”) + ylab(“Spatial Lag of crime data”)

4. Check the value of Moran's I by determining the slope of the regression line.

lm(Wsids ~ CC, data = dat)