y图中的y轴截止-par（mar）不起作用

Question

在ggplot2中进行绘制时，y轴被切断。

我试图通过使用par（mar）增加绘图区域，但是没有任何运气。

我对r很陌生，因此很可能在另一个问题中描述并解决了这个问题，但是我找不到一个可以解决我问题的问题。

非常感谢您的帮助。

library(tidyverse)
library(dplyr)
library(tidyr)
library(lubridate)
library(ggplot2)
library(grid)


df <- data.frame(date_time = seq(as.POSIXct("2018-01-01"),
                                as.POSIXct("2018-01-25"), 
                                by=(60*60*24)), temp = temp <- runif(25, 10, 20),prec = prec <- runif(25, 0, 4), par = par <- runif(25, 1000, 1500))



par_plot <- ggplot(df, aes(date_time, par)) + 
  geom_line() + 
  theme_bw() + theme(panel.border = element_blank(), panel.grid.major = element_blank(),
                     panel.grid.minor = element_blank(), axis.line = element_line(colour = "black")) +  
  theme(axis.ticks.length = unit(.2, "cm"), axis.title.y = element_text(margin = margin(t = 0, r = 0, b = 0, l = -7, "mm")), axis.text.x = element_blank(), axis.title.x = element_blank()) +
  scale_x_datetime(date_breaks = "3 days", expand = c(0.01, 0)) +
  scale_y_continuous(expand = c(0, 0), limits = c(0, 1500))

temp_plot <- ggplot(df, aes(date_time, temp)) + 
  geom_line() + 
  theme_bw() + theme(panel.border = element_blank(), panel.grid.major = element_blank(), panel.grid.minor = element_blank(), axis.line = element_line(colour = "black")) + 
  theme(axis.ticks.length = unit(.2, "cm"), axis.title.y = element_text(margin = margin(t = 0, r = 0, b = 0, l = -7, "mm")), axis.text.x = element_blank(), axis.title.x = element_blank()) +
  scale_x_datetime(date_breaks = "3 days", expand = c(0.01, 0)) +
  scale_y_continuous(expand = c(0, 0), limits = c(0, 20))

prec_plot <- ggplot(df, aes(date_time, prec)) + 
  geom_bar(stat="identity") + 
  theme_bw() + theme(panel.border = element_blank(), panel.grid.major = element_blank(), panel.grid.minor = element_blank(), axis.line = element_line(colour = "black")) + 
  theme(axis.ticks.length = unit(.2, "cm"), axis.title.y = element_text(margin = margin(t = 0, r = 0, b = 0, l = -7, "mm")), axis.text.x = element_text(angle=90), axis.title.x = element_blank()) +
  scale_x_datetime(date_breaks = "3 days", expand = c(0.01, 0)) +
  scale_y_continuous(expand = c(0, 0), limits = c(0, 4))


grid.newpage()
par(mar = c(15, 15, 15, 15))
grid.draw(rbind(ggplotGrob(par_plot), ggplotGrob(temp_plot), ggplotGrob(prec_plot), size = "last"))