Here's one solution, YMMV:
library(maps)
# Note, plot the map first to get the aspect ratio (or projection) right
map("county", xlim=range(df2VisitTrips[, c(5, 7)]), ylim=range(df2VisitTrips[,
c(4, 6)]),
col=8)
map("state", add=T)
map.axes()
for (i in 1:length(df2VisitTrips[, 1])) {
lines(df2VisitTrips[i, c(5, 7)], df2VisitTrips[i, c(4, 6)], lwd=0.2 +
df2VisitTrips[i,
3]/10, col=i+1)
}
Ray Brownrigg
On Thu, 03 Jul 2008, Richard and Barbara Males wrote:
> I have a dataset giving traffic between pairs of ports, and the
> lat/lon of each port, roughly as follows:
>
> sample data as follows
>
> > df2VisitTrips[1:4,]
>
> Origin Destination NumberOfTrips OriginLatitude OriginLongitude
> DestinationLatitude DestinationLongitude
> 1 P1 P16 1 39.45965
> -80.15633 40.76111 -79.54583
> 2 P1 P3 1 39.45965
> -80.15633 39.58861 -79.98222
> 3 P102 P108 19 36.98210 -88.21597
> 37.19667 -88.84389
> 4 P102 P109 71 36.98210
> -88.21597 37.09472 -89.13694
>
>
> I am interested in plotting variable-width lines, based on
> NumberOfTrips, between point pairs (OriginLongitude,OriginLatitude)
> and (DestinationLongitude,DestinationLatititude), e.g. a flow map
> between the ports. At some point, I may wish to add an underlay base
> map (say counties in the US), but that is not critical at this time.
>
> There seem to be many packages in R that deal with spatial data (sp,
> maps, PBSMapping, etc.), but it is unclear to me which one would work
> best for this application.
>
> Any advice gratefully appreciated.
>
> R. Males
> Cincinnati, Ohio, USA
>
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