1. INTRODUCTION TO SPATIAL
DATA ANALYSIS IN R
Richard W Wamalwa1 - MSc., MBA(Finance), BSc.
1Directorate of Academic Quality Assurance,
JKUAT – 2011
RM 610-Environmental, Spatial, GIS, 2011

2. OUTLINE
Installation of Sp in R
Data export into R
Creating spatial patterns/spatial points
Changing the coordinate referencing system
Creating a SpatialPointsDataframe
Creating and manipulating SpatialLines objects
Create the Polygon Objects
References

3. ID x y z
1 1 1 21
2 1 2 20
3 1 3 20
4 1 4 21
5 2 3 24
6 3 2 21
7 3 6 21
8 3 7 23
9 4 1 19
10 4 3 21
11 4 4 24
12 4 7 18
13 5 6 21
14 6 2 18
15 6 7 25
16 7 3 20
17 7 5 17

4. CREATING SPATIAL PATTERN
env1<-
read.table("env1.csv",sep=,",",header=TRUE)
env1
attach(data)
library(sp)
data.sp<-env1
data.sp
coordinates(data.sp)<-~x+y
class(data.sp)
plot(data.sp)
plot(data.sp,axes=TRUE)

5. SPATIAL POINT
x<-c(1,1,1,2,2,2,3,3,3)
y<-c(1,2,3,1,2,3,1,2,3)
xy<-cbind(x,y)
s<-SpatialPoints(xy)
class(s)
str(s)
bbox(s)
proj4string(s)
coordinates(s)
plot(s)

6. SPATIAL POINT – CONT’D
x1<-c(2,4,8,3,6,9,2,3,7,9,4,6,8,6,8)
y1<-rep(seq(2,6),c(3,3,4,3,2))
data<-data.frame(x1,y1)
data1<-data
attach(data1)
coordinates(data1)<-~x1+y1
summary(data1)
class(data1)
str(data1)
bbox(data1)
proj4string(data1)
coordinates(data1)

7. CHANGING THE COORDINATE
REFERENCING SYSTEM
crsnew<-CRS("+proj=longlat +ellps=WGS84")
data2<-SpatialPoints(data,proj4string =crsnew)
class(data2)
summary(data2)
plot(data1,axes=TRUE,col="red",pch=1)
plot(data1,axes=TRUE,col="blue",pch="+")

8. CREATING A
SPATIALPOINTSDATAFRAME
x2<-c(1,2,3,3,4,4,5,5,6,6,7)
y2<-rep(seq(2,6),c(1,4,2,2,2))
z2<-c(10,30,45,60,70,100,80,130,150,170,190)
data3<-data.frame(x2,y2,z2)
Converting to spatial
plot(s)
gridded(s) <- TRUE
gridded(s)
class(s)

9. SPATIALPOINTSDATAFRAME – CONT’D
summary(s)
plot(s)
gridded(s) <- FALSE
gridded(s)
class(s)
# data.frame
data(meuse.grid)
coordinates(meuse.grid) <- ~x+y
gridded(meuse.grid) <- TRUE
plot(meuse.grid) # not much good
summary(meuse.grid)

10. #CREATING AND MANIPULATING
SPATIALLINES OBJECTS
x1=cbind(c(1,5,8),c(1,4,8))
x2=cbind(c(1,9),c(4,2))
x3=cbind(c(3,9),c(1,4))
L1 = Lines(list(Line(x1)), ID="N1")
L2 = Lines(list(Line(x2)), ID="N2")
L3 = Lines(list(Line(x3)), ID="M3")
mylines= SpatialLines(list(L1,L2,L3))
plot(mylines,axes=T,grid=T)

11. SPATIALLINES OBJECTS – CONT’D
x1=cbind(rnorm(n),rnorm(n,0,0.25))
x2=cbind(rnorm(n),rnorm(n,0,0.25))
x3=cbind(rnorm(n),rnorm(n,0,0.25))
L1=Lines(list(Line(x1)),ID="mp1")
L2=Lines(list(Line(x2)),ID="mp2")
L3=Lines(list(Line(x3)),ID="mp3")
s=SpatialLines(list(L1,L2,L3))
plot(s,axes=T)

12. #CREATE THE POLYGON OBJECTS
#Step 1: Create the Polygon Objects
Sr1 = Polygon(cbind(c(2, 4, 4, 1, 2), c(2, 3, 5, 4, 2)))
Sr2 = Polygon(cbind(c(5, 4, 2, 5), c(2, 3, 2, 2)))
Sr3 = Polygon(cbind(c(4, 4, 5, 10, 4), c(5, 3, 2, 5, 5)))
Sr4 = Polygon(cbind(c(5, 6, 6, 5, 5), c(4, 4, 3, 3, 4)),
hole = TRUE)
#Step 2: Creating
Srs1 = Polygons(list(Sr1), "s1")
Srs2 = Polygons(list(Sr2), "s2")
Srs3 = Polygons(list(Sr3, Sr4), "s3/4")
#Step 3: Creating a SpatialPolygons list object
SpP = SpatialPolygons(list(Srs1, Srs2, Srs3), 1:3)
plot(SpP, col = 1:3, pbg = "white")

13. REFERENCES
Gentleman, R., Hornik, K. and Parmigiani, G.
(2008). Applied Spatial Data Analysis with R.
ISBN 978-0-387-78170-9 e-ISBN 978-0-387-
78171-6 DOI 10.1007/978-0-387-78171-6.
Thomas N O Achia (2010). Environment, Spatial
statistics and GIS Notes.