[R-sig-eco] Export Google Maps Route to R and get kilometers coordinates

[Augusto Ribas]

Hello. I have the following problem.
I have some data of fauna hit on a road in Brasil. The Road ES-060.

The data is something like this:

> head(dados)
  species km
1    Sp 6 27
2    Sp 6 21
3    Sp 1 44
4    Sp 2 47
5    Sp 5 39
6    Sp 5 20

Each line represent one dead individual, and has a register of it
species and the kilometer of the road where it was found dead.
I would like to do a plot of the deaths on a map, but i don't have the
coordinates (latitude and longitude) of where km 27 is, for example.
But looking in google maps, i was able to find the road, and i know
some points of where the road is and its respective kilometer.
Like this:

> dados.pos
        Lon       Lat            Local
1 -40.32012 -20.39675 Begin
2 -40.32477 -20.40193 KM 12
3 -40.39341 -20.54320 KM 30
4 -40.51056 -20.63095 KM 49
5 -40.55583 -20.73349 KM 66
6 -40.55161 -20.73921   End

So Begin is around kilometer 11, end is around kilometer 67 (the range
of the data), and using google street view, i could see plaques on the
road telling me which kilometer some places is, so i can get some
coordinates and which kilometer it represent.

So if i could import a route from google maps as a polygon, from end
to begin, i could try to determinate the coordinate of each kilometer.
But i could not figure out how to export from google maps to R such information.
These points i saved on google maps as an kml file and loaded on R,
using getKMLcoordinates {maptools} function. But i'm stuck on how to
proceed to the the coordinates of each kilometer of the road.
Does anyone have some idea how would i be able to do something like
this, if it is possible?

Here goes some example data and a plot of the road and the points i show above:

library(RgoogleMaps)

#example of how data is organized
species<-paste("Sp",1:6)
km<-seq(11,67,by=1)

dados<-data.frame(species=NA,km=NA)
for(i in 1:20) {
  dados[i,1]<-sample(species,1)
  dados[i,2]<-sample(km,1)
  }

head(dados)

#some points coordinates that i know
dados.pos<-structure(list(Lon = c(-40.3201206572012,
-40.3247698942156, -40.3934139596311,
-40.5105609306218, -40.5558289282114, -40.551610815962), Lat =
c(-20.3967530595136,
-20.4019278830141, -20.5432001637965, -20.6309481844606, -20.733489883797,
-20.7392078853725), Local = c("Begin", "KM 12", "KM 30", "KM 49", "KM 66",
"End")), .Names = c("Lon", "Lat", "Local"), row.names = c(NA, -6L),
class = "data.frame")

dados.pos

#one plot of the road and the know points
lat = dados.pos[c(1,6),2]
lon = dados.pos[c(1,6),1]
center = c(lat=mean(lat), lon=mean(lon))
zoom <- min(MaxZoom(range(lat), range(lon)))

MyMap <- GetMap(center=center,zoom=zoom,maptype ="roadmap")

PlotOnStaticMap(MyMap)
TextOnStaticMap(MyMap,dados.pos[,2],dados.pos[,1],labels = dados.pos[,3])

Thanks for your attention.
Best Wishes - Augusto Ribas




--
Grato
Augusto C. A. Ribas

Site Pessoal: http://augustoribas.heliohost.org
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