Plot a ggmap and add geom_tile to the same plot

Question

currently I have a file that I want to plot overlayed to a map. My script is the following:

library(ggmap)
library("ggplot2")

dataset = read.csv('stats.data')

names(dataset)=c('x','y','color')
dftotal = data.frame(x=dataset$x,y=dataset$y, col=dataset$color)

### Set a range
lat <- c(min(dataset$y),max(dataset$y))                
lon <- c(min(dataset$x),max(dataset$x)) 
bb <- c(0,1,2,3,4,5,6,7,8,9)

### Get a map
map <- get_map(location = c(lon = mean(lon), lat = mean(lat)), zoom = 13, maptype = "satellite", source = "google")
ggmap(map)
pdf(paste("map.pdf", sep=""))

palette <- c("#000000","#000099")
palette <- c(palette, "#990099","#BB0099")
palette <- c(palette, "#EE0099","#FF00AA")
palette <- c(palette, "#FF00FF","#FF77FF")
palette <- c(palette, "#77AA77","#33FF33")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")
palette <- c(palette, "#00FF00","#00FF00")

ggplot(dftotal, aes(x=x, y=y, colour=factor(col), fill=factor(col))) +
geom_tile(aes(alpha=0.5)) +
scale_x_continuous(limits = lon, expand = c(0,0)) +
scale_y_continuous(limits = lat, expand = c(0,0)) +
scale_fill_manual(values=palette,breaks = bb, labels=c("0","1","2","3","4","5","6","7","8","9 or more")) +
scale_colour_manual(values=palette,breaks = bb) +
theme(axis.text.y = element_blank()) +
theme(axis.text.x = element_blank()) +
theme(axis.title.y = element_blank()) +
theme(axis.title.x = element_blank()) +
theme(axis.ticks.y = element_blank()) +
theme(axis.ticks.x = element_blank()) +
guides(color=FALSE) +
guides(alpha=FALSE) +
guides(fill=FALSE)

If I do

map + geom_tile(data=dftotal, aes(...))

I get an error. I'm not stuck with geom_tile, I can also use something else. I want to plot the data contained in the file (it can be found here for trying it), and the color should reflect the last column. Any idea?

EDIT I add some data for everyone, instead of downloading the file.

11.2976436018,44.4748465014,20.0
11.2976436018,44.4750510851,21.0
11.2976436018,44.4752556688,3.0
11.2976436018,44.4754602525,4.0
11.2976436018,44.4756648362,4.0
11.2976436018,44.4758694198,40.0
11.2976436018,44.4760740035,4.0
11.2976436018,44.4762785872,5.0
11.2976436018,44.4764831709,7.0
11.2976436018,44.4766877546,8.0
11.2976436018,44.4768923383,10.0
11.2976436018,44.477096922,11.0
11.2976436018,44.4773015057,10.0
11.2976436018,44.4775060893,10.0
11.2976436018,44.477710673,4.0
11.2976436018,44.4779152567,0.0
11.2976436018,44.4781198404,1.0
11.2976436018,44.4783244241,1.0
11.2976436018,44.4785290078,2.0
11.2976436018,44.4787335915,22.0
11.2976436018,44.4789381751,21.0
11.2976436018,44.4791427588,22.0
11.2976436018,44.4793473425,23.0
11.2976436018,44.4795519262,21.0
11.2976436018,44.4797565099,14.0
11.2976436018,44.4799610936,16.0
11.2976436018,44.4801656773,1.0
11.2976436018,44.480370261,1.0
11.2976436018,44.4805748447,0.0
11.2976436018,44.4807794283,6.0
11.2976436018,44.480984012,9.0
11.2976436018,44.4811885957,19.0
11.2976436018,44.4813931794,36.0
11.2976436018,44.4815977631,21.0
11.2976436018,44.4818023468,37.0
11.2976436018,44.4820069305,22.0
11.2976436018,44.4822115142,15.0
11.2976436018,44.4824160978,28.0
11.2976436018,44.4826206815,28.0
11.2976436018,44.4828252652,22.0
11.2976436018,44.4830298489,21.0
11.2976436018,44.4832344326,2.0
11.2976436018,44.4834390163,4.0
11.2976436018,44.4836436,4.0
11.2976436018,44.4838481837,40.0
11.2976436018,44.4840527673,1.0
11.2976436018,44.484257351,1.0
11.2976436018,44.4844619347,20.0
11.2976436018,44.4846665184,30.0
11.2976436018,44.4848711021,30.0

Answer 1

I think switching to geom_point (I also changed the alpha and [IMO] made it easier to twiddle bits of the ggplot object) may be all that you need:

gg <- ggmap(map) + geom_point(data=dftotal, mapping=aes(x=x, y=y, colour=factor(col), fill=factor(col)), alpha=0.125)
gg <- gg + scale_x_continuous(limits = lon, expand = c(0,0)) + scale_y_continuous(limits = lat, expand = c(0,0))
gg <- gg + scale_fill_manual(values=palette,breaks = bb, labels=c("0","1","2","3","4","5","6","7","8","9 or more"))
gg <- gg + scale_colour_manual(values=palette,breaks = bb)
gg <- gg + theme(axis.text = element_blank(), axis.title = element_blank(), axis.ticks = element_blank())
gg <- gg + guides(color=FALSE, alpha=FALSE, fill=FALSE)
gg