在 r 中包装地块多次给我相同的 plot

Question

library(patchwork)
library(ggplot2)

cell_measurements = read_csv(random.csv)
measurement_types = col_names(cell_measurements)[5:9]
plot_list = list()

for (i in 1:5){
  plot_list[[i]] = ggplot(cell_measurements, aes(sapply(Injury, as.character), eval(parse(text = measurement_types[i])))) +
  geom_boxplot(aes(fill=Animal)) +
  labs(x ='Injury', y = measurement_types[i])
}

wrap_plots(plot_list)

Example data:

Animal = c(dog, dog, dog, rabbit, rabbit, rabbit)
Injury = c(0,1,0,1,0,1)
Measurement1 = c(0.1,0.2,-0.8,1.5,1.2,1.3)
Measurement2 = c(0.1,0.5,-0.9, -1.4, 1.6, -0.5)

What I expected to get were five different plots neatly arranged, instead, all five plots here are the same. They have the right labels on the x and y axis but the box plots look exactly the same.

Also, tried to each plot individually and then do wrap_plots which worked fine. Just doesn't work when I use the for loops.

Answer 1

The lazy operation of ggplot makes it so that the value of i is really only evaluated when you try to plot all three. That is, in your for loop, the i iterates over 1 through 5, but the ggplot code knows that it must reference i when it renders. Since the rendering step doesn't happen until after the for loop is done, all five instances of the lazy-ggplot objects look for i and find the same value of i = 5 .

Options:

1. Facet your plot, no need for wrap_plots . (This requires reshaping/pivoting/melting.)

    reshape2::melt(quux, c("Animal", "Injury"), variable.name = "Measurement") |> ggplot(aes(Injury, Measurement)) + geom_boxplot(aes(fill = Animal)) + facet_grid(Measurement ~., scales = "free_y")

   

   You can use tidyr::pivot_longer in place of reshape2::melt .

   You can facet them horizontally as well, though the y-axis will be split.

2. Use lapply in place of your for loop. While it seems relatively synonymous in effect , there value of i is actually different between the iterations.

    lapply(c("Measurement1", "Measurement2"), function(m) subset(quux, select = c("Animal", "Injury", m)) |> ggplot(aes(Injury, m)) + geom_boxplot(aes(fill = Animal))) |> ggplot(aes(Injury, m)) + geom_boxplot(aes(fill = Animal))) |> patchwork::wrap_plots()

   

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Data

quux <- structure(list(Animal = c("dog", "dog", "dog", "rabbit", "rabbit", "rabbit"), Injury = c(0, 1, 0, 1, 0, 1), Measurement1 = c(0.1, 0.2, -0.8, 1.5, 1.2, 1.3), Measurement2 = c(0.1, 0.5, -0.9, -1.4, 1.6, -0.5)), class = "data.frame", row.names = c(NA, -6L))