PlotGoogleMaps -Need help in bubbleGoogleMaps

Question

I am learning R and I love it so far. I am so impressed with one of the example provided in the "plotGoogleMaps" package. Is it possible to apply that my below example? please help.

The example I see in the package

    # Data preparation
    library(plotGoogleMaps)
    data(meuse)
    coordinates(meuse)<-~x+y
    proj4string(meuse) <- CRS('+init=epsg:28992')

    m<-bubbleGoogleMaps(meuse,zcol='zinc')

    m<-bubbleGoogleMaps(meuse,zcol='cadmium',layerName='Bubble plot - meuse',
                        colPalette=terrain.colors(5),strokeColor=&rdquo;)

I Would like to apply the above example map to my below data. In my example sale = zinc (in above example). And I want to display my other attributes while I am highlighting my bubble.

  library(plotGoogleMaps)
    bubblechart = read.table(text="Itemcode,sale,name,longt,latit
                        101,1112,A,-89.6171,35.24992
                   105,1540,B,-90.0154,35.10510
                   106,2200,C,-89.5213,34.93277
                   111,1599,D,-86.8642,36.34807
                   113,4500,E,-86.6125,36.19958
                   114,3569,F,-90.4611,30.02196",
                   header=TRUE,sep=",")

Please help...

Answer 1

bubbleGoogleMaps() requires you to transform your bubblechart data in a SpatialPointsDataFrame. For this you need to specify the coordinates and the reference system in which Longitude and Latitude were measured. There is a related GIS stackexchange question: Converting geographic coordinate system in R . See also the Wikipedia page of the World Geodetic System (used by GPS).

Inspect an existing SpatialPointsDataFrame

library(plotGoogleMaps)
data(meuse)
# meuse is a data frame
class(meuse)
# Specify coordinates and projection system
coordinates(meuse)<-~x+y
proj4string(meuse) <- CRS('+init=epsg:28992')
# meuse has become a "SpatialPointsDataFrame"
class(meuse)
# Which contains several objects
class(meuse@data)
class(meuse@coords)
summary(meuse@coords)
class(meuse@bbox)
class(meuse@proj4string)
help(SpatialPointsDataFrame)
# Convert meuse back to a data frame 
meusedtf <- as.data.frame(meuse)

Create your own SpatialPointsDataFrame

# Set coordinates and reference system
coordinates(bubblechart) <- ~longt +latit
proj4string(bubblechart) <- CRS("+init=epsg:4326") # WGS 84

Generate maps

m <- bubbleGoogleMaps(bubblechart, zcol='sale', max.radius = 20000)

Change the max.radius parameter to change bubble size. And change the key.entries parameter to set different boundaries on the sales values.

You can also display your sales bubbles as a R plot with:

plot(bubblechart)
points(bubblechart@coords, pch=21, cex=(bubblechart$sale)/1000, col="black", bg="blue")
bubble(bubblechart, "sale", maxsize = 2.5, main = "Sales in the US", key.entries = 2^(-1:4))

These R plots would look nicer if you add a map of the US states in the background to help identify the areas.