Superimpose one ggplot on another

Question

I have two ggplot objects as below.

library(ggplot2)

set.seed(1)
dat1 = data.frame(x = rnorm(1000), y = rnorm(1000))
dat2 = data.frame(x = rt(5000, 2))

Plot1 = ggplot(data = dat1, aes(x = x, y = y)) + geom_point()
Plot2 = ggplot(dat2) + geom_histogram(aes(x = x))

Now I would like to superimpose Plot2 on Plot1 in the left-middle part of Plot1. Desired output

For better visibility, I also wish to have some transparency with Plot2 so that the Plot1 should not be masked completely in the overlapping region.

Is there any way to achieve that? I have searched over internet for relevant information however all of them seem to be referring to add layers. My final plot will be different from just adding layers.

Answer 1

As partially suggested in a since-deleted answer, we can use patchwork::inset_element() for this.

library(patchwork)
Plot2 = ggplot(dat2) + geom_histogram(aes(x = x)) +
  theme_bw() +
  theme(
    plot.background = element_rect(fill = "#ffffffaa"),
    panel.background = element_rect(fill = "#ffffffaa"),
    axis.title = element_blank(),
    axis.text = element_blank(),
    axis.ticks = element_blank()
)
Plot1 + inset_element(Plot2, 0, 0.2, 0.3, 0.7)

I used fill="#ffffffaa", though "transparent" gives full transparency.

Answer 2

Edit after extra requirements You may use cowplot::ggdraw to superimpose the plot2-grob over plot1 positioning it within plot 1 using normalized device coordinates [0,1] + setting the background to semi-transparent using panel.background = element_rect(fill = alpha('#D3D3D3', 0.6)

• plot margins can be defined within the theme of plot2 using this
• if you want to set more plot elements to transparent, check this out (e.g. hiding the grids panel.grid = element_blank())

---

library(ggplot2)
library(cowplot)

set.seed(1)
dat1 = data.frame(x = rnorm(1000), y = rnorm(1000))
dat2 = data.frame(x = rt(5000, 2))

Plot1 = ggplot(data = dat1, aes(x = x, y = y)) + geom_point() +
  theme(plot.background = element_rect(fill='transparent', color="black"))

Plot2 = ggplot(dat2) + geom_histogram(aes(x = x)) + 
  theme(
    # add half-transparent background
    panel.background = element_rect(fill = alpha('#D3D3D3', 0.5)), 
    #                                       add border color and      linewidth if needed
    plot.background = element_rect(fill='transparent', color="black", linewidth=1)
  )

ggdraw() +
  draw_plot(Plot1) +
  draw_plot(Plot2, x = 0.05, y = 0.3, width = 0.4, height = 0.4)
# Adjust x,y,width,height as relatives of plot 1 dimensions
# here i set the width of Plot 2 to be 40 % of Plot 1's width

giving