[R-sig-Geo] How to show the color bar legend in R?

[Ferra Xu]

Based on the dataset, I computed a 3D kernel (longitude, latitude, depth) and displayed the magnitude with the sphere radius and time with color as follows. I am wondering how I can show the color bar legend. 

Also I have problem with the scale of the graph. I need to see if the balls touch or overlap each other from the graph but since the scales are not real I cannot recognize it. How can I correct it? 

library(ks) 
x <- read.csv("HK1.csv") 
y <- x[,1:3] 
fhat1 <- kde(x=y) 
n <- nrow(x) 
col <- grey((n:1)/n) 
plot(fhat1, xlim=c(0,500), ylim=c(0,250), zlim=c(0, 4.4)) 
spheres3d(y, radius=15*(x$magnitude), alpha=1, col= col) 

I tried this code (which didn't work): 

legend_image <- as.raster(matrix(grey((n:1)/n), ncol=1)) 
plot(c(0,2),c(0,200),type = 'n', axes = F, xlab = '', ylab = '', main =  'time scale') 
text(x=1.5, y = seq(0,200,l=5), labels = seq(0,200,l=5)) 
rasterImage(legend_image, 0, 0, 1, 1) 

And this one in "plotrix" package: 

testcol<- col 
col.labels<- seq(0,200, l=5) 
color.legend(600, 0, 601,200,col.labels,testcol,gradient="y") 

But it gives me this error: 

Error in rect(xleft, ybottoms, xright, ytops, col = col, lty = 0) : 
plot.new has not been called yet 

Also I used legend() in Graphics library: 

legend("right", legend=seq(0,200,l=20), fill= colfunc(20), title="Time Scale") 

But it gives me the legend in a separate window. Here is my data: 

 longitude         latitude        depth             time          magnitude 

422.697323  164.19886   2.457419    8.083796636  0.83367586 
423.008236  163.32434   0.5551326   37.58477455  0.893893903 
204.733908  218.36365   1.9397874   37.88324312  0.912809449 
203.963056  218.4808    0.3723791   43.21775903  0.926406005 
100.727581  46.60876    1.4022341   49.41510519  0.782807523 
453.335182  244.25521   1.6292517   51.73779175  0.903910803 
134.909462  210.96333   2.2389119   53.13433521  0.896529401 
135.300562  212.02055   0.6739541   67.55073745  0.748783521 
258.237117  134.29735   2.1205291   76.34032587  0.735699304 
341.305271  149.26953   3.718958    94.33975483  0.849509216 
307.138925  59.60571    0.6311074   106.9636715  0.987923188 
307.76875   58.91453    2.6496741   113.8515307  0.802115718 
415.025535  217.17398   1.7155688   115.7464603  0.875580325 


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