Question 49354 in Photoshop Question posted in
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How to place multiple plots at specific coordinates using ggplot? – Photoshop

Many questions have been asked before about overlaying multiple plots in ggplot. However, my question is slightly different.

Basically, I am trying to plot a list of ggplot objects at specific coordinates on a graphic of a grid (that is created using ggplot). Hopefully my example below will explain more clearly.

To begin, create some data:

set.seed(100)
m <- matrix(runif(9, -1, 1), ncol = 3)
rownames(m) <- colnames(m) <- LETTERS[1:3]
m[lower.tri(m)] = t(m)[lower.tri(m)]
diag(m) <- 0
col1 <- colorRampPalette(RColorBrewer::brewer.pal(10,"BrBG"))

Then Im reshaping the data and creating the grid graphic to match the size of my data matrix:

df <- reshape2::melt(m)
df$abs <- abs(df$value)
df$Var1 <- factor(df$Var1, levels = colnames(m))


ggrid <- ggplot(df, aes(x = Var1, y = Var2, fill = value)) +
  geom_tile(aes(width = 1, height = 1), fill = NA, color = "grey50") +
  scale_x_discrete(position = "top", expand = c(0, 0)) +
  scale_y_discrete(limits = rev(levels(df$Var1)), expand = c(0, 0)) +
  theme_bw() +
  theme(
    aspect.ratio = 1,
    panel.grid = element_blank()
  )

The above code creates this:

gird

Then I am creating a list of plots (in this case multiple pie charts).

plot_list <- list()
for(i in 1:9){
 plot_list[[i]] <-  ggplot(df, aes(x = "", y = value, fill = Var1)) +
   geom_col(color = "black") +
   coord_polar(theta = "y") +
   theme_void() +
   theme(legend.position = 'none')
}

So, now the plot_list object contains 9 ggplot pie charts. What I’m trying to do is place the pie charts in the appropriate position on the grid. For example, plot_list[[1]] would be in position A,A on the grid… plot_list[[2]] -> A,B…continuing row-wise.

Any suggestions as to how I could achieve this. Ideally, my final goal is to make this work generically (that is, for any size grid/number of pie charts)

EDIT: To clarify, I would like my output to look like this (which I made in photoshop):

example_plot

That is, I’m trying to place each pie chart in the appropriate place on top of the ggrid object.

Tags:

2

Answers


  1. 0

    You can use ggmatrix from GGally.

    library(ggplot2)
library(GGally)
ggmatrix(plot_list, nrow = 3, ncol = 3, xlab = "Var1", ylab = "Var2", xAxisLabels = c("A", "B", "C"), yAxisLabels = c("A", "B", "C"))

    Created on 2023-04-24 with reprex v2.0.2

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  2. 0

    One option to add your pie charts on top of your ggrid plot would be to use annotation_custom. To this end I first create a dataframe containing the numeric positions to place the pies and the plots as another column. Afterwards you could use e.g. purrr::pmap to loop over the rows of this df and add the pies using multiple annotation_custom layers:

    library(ggplot2)
library(purrr)

plot_list <- lapply(seq(9), function(i) {
  ggplot(df, aes(x = "", y = value, fill = Var1)) +
    geom_col(color = "black") +
    coord_polar(theta = "y") +
    theme_void() +
    theme(legend.position = "none")
})

pie_grid <- expand.grid(
  as.numeric(factor(unique(df$Var1))),
  as.numeric(factor(unique(df$Var2)))
)
pie_grid$plot <- plot_list

ggrid +
  purrr::pmap(pie_grid, function(Var1, Var2, plot) {
    annotation_custom(
      grob = ggplotGrob(plot),
      xmin = Var1 - .5, xmax = Var1 + .5,
      ymin = Var2 - .5, ymax = Var2 + .5
    )
  })

    enter image description here

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