EvaluationDashboard.com

I decided to make a more advanced map, one with some relevance to my graduate studies in evaluation and educational psychology. This map shows geographic variation in third grade reading proficiency as measured by the 2005 Minnesota Comprehensive Assessment (MCA). Click on the thumbnail to enlarge:

Merging test scores to the attribute data frame was difficult. The attribute data frame must evidently remain sorted in the same order in which it was converted to an sp class object. I found this out after merging district test scores to the attribute data frame and finding that Cannon Falls had migrated up to Minneapolis. I created a row number variable to re-sort the data frame back to its original order before adding it back to the sp object. I’m betting there is a better way to achieve the same type of join. In the future, I will probably join additional variables to the DBF portion of the SHP file before calling it into R.

Here is the script:

library(maptools)
library(rgdal)
library(RColorBrewer)
library(classInt)

#map it
plot(districts, density=16, col="grey", axes=T, cex.axis=.75) #hatches missing data
plot(districts, col=colcode, add=T)
text(coordinates(districts), labels=districts$SD_NAME.x, cex=.5)
title(main="Percentage of Third Graders Reading Proficiently in 2005", sub="Created with R",font.sub=2)
title(xlab="Longitude",ylab='Latitude',cex.lab=.75,line=2.25)
legend(-94.1, 45.4, legend=names(attr(colcode, "table")), fill=attr(colcode, "palette"), cex=0.75, bty="n")


Sources of data and code include:
http://education.state.mn.us/
http://www.metrogis.org/
http://geography.uoregon.edu/GeogR/index.html

I have been learning R software for statistical computing. I have used it for all of my homework assignments in EPSY 8261 (Probability and Inference) and 8262 (Regression and the General Linear Model). My prof has an R blog here: http://rguide.blogspot.com/.

I envision bridging my studies in educational psychology (quantitative methods, evaluation) with my interest in spatial analysis and mapping. I read yesterday that APA’s science directorate is trying to encourage greater use of GIS in psychological research. You can read more here: http://www.apa.org/science/psa/feb08gis.html.

I decided to explore R’s mapping capabilities today. Here are a couple findings: -The shapefiles package is not really necessary. -The maptools package can read and display shapefiles, but the author encourages converting shapefiles into sp class or polylist objects. -Once shapefiles are converted, one can use the maptools plot.polylist polygon helper function.

Pat Bartlein at the University of Oregon recommends the following packages: sp, maptools, rgdal, maps, mapproj, mapdata, classInt, scatterplot3d, and RColorBrewer. He created a great website for folks like me who are starting out using R for geography: http://geography.uoregon.edu/GeogR/index.html. Thanks, Pat!

Applied researchers in the Twin Cities unfamiliar with GIS should know that the Metropolitan Council and its MetroGIS initiative have done a great job of collaborating with local entities to make a ton of data available at no charge: http://www.metrogis.org/.

I prefer ArcGIS for making maps and performing spatial analyses. I use MapInfo at work because our IT/geographer person prefers it. Mapping with R is similar to statistical computing in R–it’s a blank portrait waiting for color and texture, whereas SPSS and commercial GIS software are like the Etch A Sketch.

Click on the thumbnail for a large version of the Twin Cities map I created with R:

Here is the script:

library(maptools)
library(rgdal)
counties=readShapePoly(file.choose(),proj4string=CRS("+proj=utm +zone=15 +ellps=GRS80 +datum=NAD83")) #choose MetroGIS' county.shp
counties=spTransform(counties, CRS=CRS("+proj=longlat"))
summary(counties)
#capitalize first letter of county names
capwords cap tolower(substring(s,2)), sep = "", collapse = " " )
sapply(strsplit(s, split = " "), cap, USE.NAMES = !is.null(names(s)))
}
names=capwords(as.vector(counties$CO_NAME))
names
library(RColorBrewer)
display.brewer.all() #check out the color options
cols water=readShapePoly(file.choose(),proj4string=CRS("+proj=utm +zone=15 +ellps=GRS80 +datum=NAD83")) #choose MetroGIS' hydro_luse2000.shp
water=spTransform(water, CRS=CRS("+proj=longlat"))
coordinates(counties) #centroids
plot(counties,col=cols,axes=T,cex.axis=.75) #plot function in maptools package
plot(water,col='#6BAED6',border=NA,add=T)
text(coordinates(counties), labels=names, cex=.75)
title(main="Twin Cities Metro Area",sub="Created with R",font.sub=2)
title(xlab="Longitude",ylab='Latitude',cex.lab=.75,line=2.25)