psych (version 1.0-77)

cities: Distances between 11 US cities

Description

Airline distances between 11 US cities may be used as an example for multidimensional scaling or cluster analysis.

Usage

data(cities)

source

http://www.timeanddate.com/worldclock/distance.html

Details

An 11 x11 matrix of distances between major US airports. This is a useful demonstration of multiple dimensional scaling.

city.location is a dataframe of longitude and latitude for those cities.

Note that the 2 dimensional MDS solution does not perfectly capture the data from these city distances. Boston, New York and Washington, D.C. are located slightly too far west, and Seattle and LA are slightly too far south.

Examples

data(cities)
city.location[,1] <- -city.location[,1]
if(require(maps)) {map("usa")
title("MultiDimensional Scaling of US cities")
points(city.location)} else {plot(city.location, xlab="Dimension 1", ylab="Dimension 2",main ="multidimensional scaling of US cities")}
city.loc <- cmdscale(cities, k=2) #ask for a 2 dimensional solution  round(city.loc,0) 
city.loc <- -city.loc 
city.loc <- rescale(city.loc,mean(city.location),sd(city.location))
points(city.loc,type="n") 
text(city.loc,labels=names(cities))