Basic leaflet mapping in R

leafletMap.R

#Load the library and make a basic map
library(leaflet)
leaflet() %>% addTiles()


#Show a map with a satellite picture on it 
leaflet() %>% 
  addTiles(urlTemplate="http://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}")

#Make a demo fake data set
set.seed(100)
myData <- data.frame(Latitude = runif(100, -80,80), 
                     Longitude = runif(100, -180,180),
                     measurement1 = rnorm(100, -3, 2), 
                     Year = round(runif(100, 1975,2015)))

#Plot sites on an interactive map
leaflet() %>% 
  addTiles() %>%
  addCircles(data=myData, lat = ~Latitude, lng = ~Longitude)

#Make a label for the next map
myData$info <- paste0("Year: ", myData$Year, 
                      "<br> Value: ", round(myData$measurement1, 3))

#make some colors!

#colors

#grab a palette
library(RColorBrewer)

pal <- brewer.pal(11, "Spectral")

#now make it more continuous 
#as a colorRamp
pal <- colorRampPalette(pal)

#now, map it to your values
library(classInt)

palData <- classIntervals(myData$measurement1, style="quantile")

#note, we use pal(100) for a smooth palette here
#but you can play with this
myData$colors <- findColours(palData, pal(100))

#Put it all on a map!
leaflet() %>% 
  addTiles() %>%
  addCircles(data=myData, lat = ~Latitude, lng = ~Longitude,
             color = ~colors, popup = ~info)