Storing plots as variables in R

Question

Hello Stack community,

For my project, I am visualizing impulse response function plots in R. I am trying to store each plot as an object in R (see PART1 of the code) in order to later append all of them in one plot (using cowplot library), as a facet chart (see PART 2 of the code). However, ultimate result of the code is an empty chart with only titles at the top.

I believe reason for empty plot should be that R stores my plots as empty objects

I would greatly appreciate your help.

R code below:

#PART 1: Making IRF plots and storing them as objects

plot.1 <- plot(irf(df, impulse = "abc", response = "abc", n.ahead = 8, ortho = TRUE, runs = 1000, seed = 1))
plot.2 <- plot(irf(df, impulse = "abc", response = "def", n.ahead = 8, ortho = TRUE, runs = 1000, seed = 1))
plot.3 <- plot(irf(df, impulse = "abc", response = "ghi", n.ahead = 8, ortho = TRUE, runs = 1000, seed = 1))
plot.4 <- plot(irf(df, impulse = "abc", response = "jkl", n.ahead = 8, ortho = TRUE, runs = 1000, seed = 1))

#PART 2: making facet

library(cowplot)
plot_grid(plot.1, plot.2, plot.3, plot.4, rremove("x.text"), 
          labels = c("A", "B", "C", "D"),
          ncol = 2, nrow = 2)

G. Grothendieck · Accepted Answer · 2022-01-28T15:48:40.523

1) recordPlot Use recordPlot to record each plot.

library(cowplot)
library(irtoys)

plot(irf(Scored2pl, items=c(2,3,7)), co=NA, ask = FALSE); plot1 <- recordPlot()
plot(irf(Scored2pl), co="red", label=TRUE, ask = FALSE); plot2 <- recordPlot()
plot(irf(Scored2pl), co="blue", label=TRUE, ask = FALSE); plot3 <- recordPlot()
plot(irf(Scored2pl), co="green", label=TRUE, ask = FALSE); plot4 <- recordPlot()

plot_grid(plot1, plot2, plot3, plot4, labels = LETTERS)

2) formula cowplot also accepts a formula. The output is the same as above.

library(cowplot)
library(irtoys)

plot1 <- ~ plot(irf(Scored2pl, items=c(2,3,7)), co=NA)
plot2 <- ~ plot(irf(Scored2pl), co="red", label=TRUE)
plot3 <- ~ plot(irf(Scored2pl), co="blue", label=TRUE)
plot4 <- ~ plot(irf(Scored2pl), co="green", label=TRUE)

plot_grid(plot1, plot2, plot3, plot4, labels = LETTERS)

score 1 · Answer 2 · answered Jan 27 '22 at 13:57

You cannot directly store plots this way in R. Unlike most other functions in R, the plot generic draws the plot as a side effect, and typically does not return an object that can be used to recreate the plot again (as would be required for the objects plot.1, plot.2 etc) to do what you want them to do here.

To get them to work in cowplot, you need to wrap the plot calls in a function that will draw the plot, and pass these to cowplot::ggdraw.

Of course, I don't have your data, so will show here a simple example using base R plots

library(gridGraphics)
library(cowplot)

plot1 <- ggdraw(function() plot(x = 1:10, y = 1:10))
plot2 <- ggdraw(function() plot(x = 1:10, y = 10:1))
plot3 <- ggdraw(function() plot(x = 1:10, y = c(1:5, 5:1)))
plot4 <- ggdraw(function() plot(x = 1:10, y = c(10:6, 6:10)))

plot_grid(plot1, plot2, plot3, plot4, labels = LETTERS[1:4])

Storing plots as variables in R

2 Answers2