As of January 2006, there are 60 cities in the contiguous U.S. with population size
larger than \(300000\). We extracted information of the cities from the data
delivered by maps package. Variables coord and cartesian are
two identical representations of locations, which can be mutually converted by
sphere.convert.
Usage
data(cities)Format
a named list containing
- names
a length-\(60\) vector of city names.
- coord
a \((60\times 2)\) matrix of latitude and longitude.
- cartesian
a \((60\times 3)\) matrix of cartesian coordinates on the unit sphere.
- population
a length-\(60\) vector of cities' populations.
Examples
# \donttest{
## LOAD THE DATA AND WRAP AS RIEMOBJ
data(cities)
myriem = wrap.sphere(cities$cartesian)
## COMPUTE INTRINSIC/EXTRINSIC MEANS
intmean = as.vector(riem.mean(myriem, geometry="intrinsic")$mean)
extmean = as.vector(riem.mean(myriem, geometry="extrinsic")$mean)
## CONVERT TO GEOGRAPHIC COORDINATES (Lat/Lon)
geo.int = sphere.xyz2geo(intmean)
geo.ext = sphere.xyz2geo(extmean)
# }