Thank @paul I am trying to follow your suggestion
> map.marion <- get_map("Marion Island",zoom=9)
> dis_map <- ggmap(map.marion)
> dis_map +
> geom_point(data=gdat,aes(x = x, y = y, z = z, fill = z)) +
> geom_tile() +
> #coord_equal() +
> geom_contour(color = "white", alpha = 0.5) +
> geom_point(data = Space, mapping = aes(Longitude, Latitude),
> shape=1, inherit.aes = FALSE)+
> scale_fill_distiller(palette="Spectral", na.value="white",limits=c(0,0.4)) +
> #scale_x_reverse()+
> theme_bw()+
> ggtitle("Chlorophyll-a distribution")+
> ylab("Latitude S") + xlab("Longitude E")+
> labs(fill = "Chl-a (mg/m3)")
I think I am doing a mistake writing twice geom_point since R gives
Warning: Ignoring unknown aesthetics: z
Error: stat_contour requires the following missing aesthetics: z
How would you write it?