for循环中的多个图忽略参数

Question

我正在尝试生成10对地块，每页地块有几对，并且正在使用for循环来构造对。但是，这些图将作为单独的图而不是页面发送到设备。

下面的MWE对于基本图形和ggplot版本具有相同的构造，但是基本图形有效，而ggplot无效。我该怎么做才能使第二版中的分页正确？

library(ggplot2)
attach(mtcars)

# correct configuration
par(mfrow=c(2,2))
for (ii in 1:3){
  vars <- c("wt", "disp", "wt")
  plot(get(vars[ii]), mpg)
  hist(get(vars[ii]))
}

# places each on separate plot
par(mfrow=c(2,2))
for (ii in 1:3){
  vars <- c("wt", "disp", "wt")
  p <- ggplot(mtcars, aes(get(vars[ii]), mpg)) + geom_point(size=4)
  plot(p)
  p <- ggplot(mtcars, aes(get(vars[ii]))) + geom_histogram()
  plot(p)
}

detach(mtcars)

Answer 1

这是使用cowplot::plot_grid的一种方法。 plot_duo函数在ggplot2 v3.0.0中使用tidyeval方法

# install.packages("ggplot2", dependencies = TRUE)

library(rlang)
library(dplyr)
library(ggplot2)
library(cowplot)

plot_duo <- function(df, plot_var_x, plot_var_y) {

  if (is.character(plot_var_x)) {
    print('character column names supplied, use ensym()')
    plot_var_x <- ensym(plot_var_x)
  } else {
    print('bare column names supplied, use enquo()')
    plot_var_x <- enquo(plot_var_x)
  }

  if (is.character(plot_var_y)) {
    plot_var_y <- ensym(plot_var_y)
  } else {
    plot_var_y <- enquo(plot_var_y)
  }

  pts_plt <- ggplot(df, aes(x = !! plot_var_x, y = !! plot_var_y)) + geom_point(size = 4)
  his_plt <- ggplot(df, aes(x = !! plot_var_x)) + geom_histogram()

  duo_plot <- plot_grid(pts_plt, his_plt, ncol = 2)
}

### use character column names
plot_vars1 <- c("wt", "disp", "wt")
plt1 <- plot_vars1 %>% purrr::map(., ~ plot_duo(mtcars, .x, "mpg"))
#> [1] "character column names supplied, use ensym()"
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
#> [1] "character column names supplied, use ensym()"
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
#> [1] "character column names supplied, use ensym()"
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

plot_grid(plotlist = plt1, nrow = 3)

### use bare column names
plot_vars2 <- alist(wt, disp, wt)
plt2 <- plot_vars2 %>% purrr::map(., ~ plot_duo(mtcars, .x, "mpg"))
#> [1] "bare column names supplied, use enquo()"
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
#> [1] "bare column names supplied, use enquo()"
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
#> [1] "bare column names supplied, use enquo()"
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

plot_grid(plotlist = plt2, nrow = 3)

要将地块分成多个页面，我们可以使用gridExtra::marrangeGrob

ml1 <- marrangeGrob(plt, nrow = 2, ncol = 1)

# Interactive use
ml1

# Non-interactive use, multipage pdf
ggsave("multipage.pdf", ml1)