I have been experimenting with the issue discussed below.  With anther data set, I have found that when there are more than 3 pie slices the overall pie size gets distorted.


I am using segmentGoogleMaps to plot pie charts at various locations in the US.  I have notice that the sizes between the pie charts do not preserve their true ratio.  In the example below,  'berry' is smaller than 'apple'.  When plotting, it appears 'berry' is slightly bigger than 'apple'.  In addition, is there a way to preserve size ratios between layers.


name

a

b

c

e

Total

Lat

Lon

berry

66873

6368

48790

221739

343770

31.0661

-93.206

apple

17863

14349

15525

478877

526614

34.66447

-98.4069



fileName = paste("exampleSegment",".csv",sep = "")
  rawData = read.csv(fileName,header = T)

  loc<- data.frame(Lat=rawData$Lat,Lon = rawData$Lon,rawData)
coordinates(loc) <- ~Lon+Lat
proj4string(loc) <- CRS("+proj=longlat")

m2 <- segmentGoogleMaps(loc,zcol=c('a','b','c','e'),mapTypeId='ROADMAP'
  ,filename='excess.htm',max.radius = 300000, colPalette = c('green4','yellow','lightcoral','brown1'),strokeColor = 'black') #,add = T,do.sqrt = F)




***********************
Shawn C. McKay Ph.D.
The RAND Corporation
1776 Main Street
Santa Monica, CA 90407
smckay@rand.org<mailto:smckay@rand.org>
310-393-0411 ex 6823
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