Set map extent to min and max lat/long using qmap

Question

I have point data for a number of individuals and generate maps for each individual using a for loop. Some individuals travel much further than others on a daily basis so the extent/zoom for each individual needs to be different. Within a loop I have been using the centroid for each individual to generate a map with qmap but need to also get a unique extent/zoom for each individual.

I have generated a reproducible example below where IndID BBB has a small home range (does not travel far) compared to IndID AAA, who is wide ranging. For each individual I export a map, although below I have written the resulting maps to a list object for reproducibility sake.

library(ggmap)
set.seed(123)
dat1 <- data.frame(IndID = rep("AAA", 100),
                   Lat = sample(seq(45.500,45.900, 0.001), 100,  replace = T),
                   Long = sample(seq(111.2,111.805, 0.001), 100, replace = T)*-1)


dat2 <- data.frame(IndID = rep("BBB", 100),
                   Lat = sample(seq(45.655,45.700, 0.001), 100,  replace = T),
                   Long = sample(seq(111.4,111.5, 0.001), 100, replace = T)*-1)


dat <- rbind(dat1, dat2)

###Look at the Points
MeanLat <- mean(dat$Lat, na.rm = TRUE) 
MeanLon <- mean(dat$Long, na.rm = TRUE) 

BaseMap <- qmap(location = c(lon = MeanLon, lat = MeanLat), zoom = 10,  maptype = "terrain")

BaseMap + geom_point(aes(x = Long, y = Lat, color = IndID), data = dat, size = 4)+
  scale_colour_manual(values = c("darkblue","red"),drop=FALSE) 

###Make list and run loop
Maps <- list()

for( i in unique(dat$IndID)){
  #Subset data to IndID i
  IndDat <- subset(dat, IndID == i)

  #Get mean lat and long for IndID i
  MeanLat <- mean(IndDat$Lat, na.rm = TRUE) 
  MeanLon <- mean(IndDat$Long, na.rm = TRUE) 

  #Get base map
  BaseMap <- qmap(location = c(lon = MeanLon, lat = MeanLat), zoom = 10,  maptype = "terrain")

  #plot points on base map 
  FnlMap <- BaseMap + geom_point(aes(x = Long, y = Lat, color = IndID), data = IndDat, size = 4)+
    scale_colour_manual(values = c("darkblue","red"),drop=FALSE) 

  #Store in list object
  Maps[[i]] <- FnlMap
}

Maps$AAA
Maps$BBB

In this instance the zoom argument to qmap is set to 10. This is appropriate for AAA, but not for BBB, which would be better viewed with a zoom of 13.

I am generating maps for many individuals and want to define an appropriate zoom/extent for each individual within the loop. Rather than relying on the zoom argument I wanted to use the min and max lat and long values to set the extent but this does not seem possible in qmap.

Any suggestions would be appreciated.

Set map extent to min and max lat/long using qmap

0 Answers0