How to Overlay an Image on to a Ggplot

Way to overlay an image on each ggplot object in a list using grid.raster?

Here is a possibile solution:

library(ggplot2)
library(purrr)
library(cowplot)
library(gridExtra)
library(magick)

stock_image <- image_read_svg('http://jeroen.github.io/images/tiger.svg', width = 400)

# Make 4 ggplot objects for example
any_ggplot1 <- qplot(mtcars$hp, mtcars$mpg)
any_ggplot2 <- qplot(mtcars$drat, mtcars$mpg)
any_ggplot3 <- qplot(mtcars$wt, mtcars$cyl)
any_ggplot4 <- qplot(mtcars$disp, mtcars$cyl)

# Make a list of them
plot_list <- list(any_ggplot1, any_ggplot2, any_ggplot3, any_ggplot4)

new_plot_list <- purrr::map(plot_list, function(x) {
    ggdraw() +
      draw_image(stock_image, x = 0.25, y = 0.25, scale=0.25) +
      draw_plot(x)
})

grid.arrange(grobs=new_plot_list)

Inserting an image to ggplot2

try ?annotation_custom in ggplot2

example,

library(png)
library(grid)
img <- readPNG(system.file("img", "Rlogo.png", package="png"))
g <- rasterGrob(img, interpolate=TRUE)

qplot(1:10, 1:10, geom="blank") +
  annotation_custom(g, xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf) +
  geom_point()

How to add a black overlay semi transparent layer above the background image in r?

Based on this answer I tried annotate() instead of geom_rect(), which does the trick:

ts_all_long %>% 
  filter(Country.Region == "Brazil") %>% 
  
  ggplot(aes(x = date, y = Confirmed_daily)) +
  background_image(readJPEG("/home/johannes/Downloads/coronavirus-4972480_1920.jpg")) +
  annotate("rect", xmin = min(ts_all_long$date), xmax = max(ts_all_long$date), ymin = -Inf, ymax = Inf,
            fill = "black", alpha = 0.3) +
  geom_area(size = 1, col = "#f08080", fill = "#f08080", alpha = 0.5)

^{Created on 2021-04-20 by the reprex package (v2.0.0)}

However, I think it would actually look better to do something like this:

ts_all_long %>% 
  filter(Country.Region == "Brazil") %>% 
  
  ggplot(aes(x = date, y = Confirmed_daily)) +
  background_image(readJPEG("/home/johannes/Downloads/coronavirus-4972480_1920.jpg")) +
  geom_area(size = 1, col = "white", fill = "#f08080", alpha = 0.5)

^{Created on 2021-04-20 by the reprex package (v2.0.0)}

how to fit the plot over a background image in R and ggplot2

You can set width and height arguments in rasterGrob both equal to 1 "npc", which will force the image to fill the plot area. Then specify the height and width of the image when you save it to get the aspect ratio you desire. Theme and scale_y_reverse options can be used to control the appearance of the axes as demonstrated also below. note that we can also use the expand parameter to ensure that the axes do not extend further than the image or data.

g <- rasterGrob(img, width=unit(1,"npc"), height=unit(1,"npc"), interpolate = FALSE)

g_ct <- ggplot(data=df_ct) +
  annotation_custom(g, -Inf, Inf, -Inf, Inf) +
  geom_path(aes_string(x=df_ct$X1, y=df_ct$X0), color='red', size=1) +
  scale_y_reverse("", 
                  labels = c(min(df_ct$X0), rep("", length(seq(min(df_ct$X0), max(df_ct$X0), 5))-2),max(df_ct$X0)), 
                  breaks = seq(min(df_ct$X0), max(df_ct$X0), 5),
                  expand = c(0,0)) +
  theme(plot.margin = unit(c(5,5,5,5), "mm"),
        axis.line.x = element_blank(),
        axis.ticks.x = element_blank(),
        axis.text.x = element_blank(),
        axis.line.y = element_blank(),
        axis.ticks.y = element_line(size = 1),
        axis.ticks.length = unit(5,'mm')) +
  scale_x_continuous("")
g_ct

ggsave('test.png', height=5, width = 2, units = 'in')

Some data:

df_ct <- data.frame(X0 = 0:100)
df_ct$X1 = sin(df_ct$X0) +rnorm(101)

and a background image:

https://i.stack.imgur.com/aEG7I.jpg

Use ggplot to plot over an image with legend

The real "magic" for this is just fullpage=FALSE in the call to ggimage(), but you'll have to clean up axes a bit then:

ggimage(r, fullpage = FALSE, scale_axes = TRUE) +
 geom_point(aes(x = x, y = y, colour = SEX), 
            data = toy, size = I(1), fill = NA) +
  labs(x=NULL, y=NULL) +
  theme(axis.text=element_blank()) +
  theme(axis.ticks=element_blank())

You should prbly clean up the legend, too and I'd suggest lightening the base image a bit since it will be difficult to see the contrast between it and the colors you're going to overlay (unless they're large objects).

heat map with image as background

Something like this?

library(ggplot2)
data(hadley, package="ggmap")
img <- hadley
set.seed(1)      # for reproducible example
df  <- data.frame(x=rnorm(100,mean=c(150,250),sd=25),
                  y=rnorm(100,mean=480, sd=20))

ggplot(df, aes(x,y))  + 
  annotation_raster(img, xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf)+
  stat_density2d(geom = "polygon", aes(fill=..level..)) + 
  geom_point(size=0.5)+
  scale_fill_gradient(low="green",high="red") + 
  scale_x_continuous(limits=c(0,dim(img)[2]),expand=c(0,0))+
  scale_y_continuous(limits=c(0,dim(img)[1]),expand=c(0,0))+
  coord_fixed()

The main idea is to use geom="polygon" with aes(fill=..level..). The image itself can be added using annotation_raster(...) as described in this post.

With sincere apologies to Hadley Wickham.

---

Related Topics