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I have a data frame (X) that looks like this:

code   cluster    name   longt      latit
101      1         A   -89.6171 35.24992
105      1         B   -90.0154 35.10510
106      2         C   -89.5213 34.93277
111      1         D   -86.8642 36.34807
113      3         E   -86.6125 36.19958
114      2         F   -90.4611 30.02196

I would like to plot the observations based on the cluster using plotGoogleMaps function. I have done the following:

X1 <- X
coordinates(X1) <- ~longt+latit # convert to SPDF
proj4string(X1) <-  CRS("+proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0")
ic <- iconlabels(X1$cluster, height=10,colPalette=rainbow(4), icon=TRUE)
m <- plotGoogleMaps(X1,filename='myMap.htm', iconMarker=ic, 
    colPalette=rainbow(4),mapTypeId='ROADMAP',layerName = 'Clusters')

But I am facing two problems:

  1. when I use rainbow(3) as colors, I get only 2 colors in my legend (instead of 3). But when I use rainbow(4), I get 4 colors.

  2. The legend doesn't represent the clusters, i.e. I don't get a color for each cluster (like one color for #1, one color for #2, one color for #3,...)

  3. The Icons plotted on google map are only 2 colors (Green and Red). Clusters 1 and 2 are all red, and cluster 3 is green. I would like to obtain a distinct color for each cluster.

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1 Answer 1

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Looking at the examples provided with the ?iconlabels function, the author uses the column landuse from the meuse dataset. That column is from class factor.

So I tried to convert your column cluster from class integer to class factor and it worked.

X = read.table(text="code,cluster,name,longt,latit
                    101,1,A,-89.6171,35.24992
                    105,1,B,-90.0154,35.10510
                    106,2,C,-89.5213,34.93277
                    111,1,D,-86.8642,36.34807
                    113,3,E,-86.6125,36.19958
                    114,2,F,-90.4611,30.02196",
                header=TRUE,sep=",")

X$cluster = as.factor(X$cluster)
X1 <- X

require(sp)
coordinates(X1) <- ~longt+latit # convert to SPDF
proj4string(X1) <-  CRS("+proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0")

require(plotGoogleMaps)
ic <- iconlabels(X1$cluster,height=10,icon=TRUE,colPalette=rainbow(3))
m <- plotGoogleMaps(X1,zcol="cluster",filename='myMap.htm',iconMarker=ic, 
                    colPalette=rainbow(3),mapTypeId='ROADMAP',layerName='Clusters')


enter image description here

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  • Thank you very much @Andre Silva. That is exactly what I was missing.
    – H_A
    Nov 29, 2014 at 2:16

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