Representing different layers in a ggplot map! R - r

Question

M intention is to represent 3 different layers of information in a ggplot map:
1. The map itself using a MULTIPOLYGON file
2. Kriging estimations using geom_tile()
3. datapoints using geom_point()
I used the following script:
library(rnaturalearth)
library(rnaturalearthdata)
world <- ne_countries(scale = "medium", returnclass = "sf")
windows()
ggplot(data = world) +
geom_sf(color="black",fill="grey90") +
theme(panel.background = element_blank()) +
coord_sf(xlim = c(-12.3, 95), ylim = c(70, 22), expand = FALSE) +
geom_tile(data = myKrige, aes(x= x1, y= x2, fill =var1.pred)) +
geom_point(data = roh, aes(x = LON, y = LAT))
In this script I used three datasets: world (a MULTIPOLYGON obtained from rnaturalearthdata), myKrige (data frame obtained from a spatialPointsDataFrame) and roh (data frame with latitude and longitude data points).
This is the figure my script produces:
As you can see the different layers are on top of each other. But I would like to merge nicely the geom_tile with the base plot.
Any idea how can I do it easily. Or should I rethink the complete figure?

Answer 1

Here is starting point, following an example from https://rpubs.com/nabilabd/118172
library(rnaturalearth)
library(rnaturalearthdata)
library(ggplot2)
library(sf)
world <- ne_countries(scale = "medium", returnclass = "sf")
df <- data.frame(x=rnorm(10,sd = 3),
y=rnorm(10,sd = 3))
df <- sf::st_as_sf(df, coords=c("x","y"), crs = 4326, agr = "constant", remove = F)
ggplot(data = world) +
geom_sf() +
geom_sf(data=df) +
# The idea would then to add add a scale_fill_gradient() such
# as in https://rpubs.com/nabilabd/118172 , but I dont know
# how the kring data should look like.
coord_sf(xlim = c(-10,10), ylim=c(-10,10))
# example
lzn.kriged %>% as.data.frame %>%
ggplot(aes(x=x, y=y)) + geom_tile(aes(fill=var1.pred)) + coord_equal() +
scale_fill_gradient(low = "yellow", high="red") +
scale_x_continuous(labels=comma) + scale_y_continuous(labels=comma) +
theme_bw()