沿x和y轴的R ggplot自定义面板网格

Question

下面是没有任何panel.grid的绘图的可重现的R脚本

require(ggplot2)
library(ggrepel)
# Create the data frame.
sales_data <- data.frame(
  emp_name = rep(c("Sam", "Dave", "John", "Harry", "Clark", "Kent", "Kenneth", "Richard", "Clement", "Toby", "Jonathan"), times = 5), 
  month = as.factor(rep(c("Jan", "Feb", "Mar", "Jan", "Feb", "Mar", "Jan", "Feb", "Mar", "Jan", "Jan"), times = 5)),
  dept_name = as.factor(rep(c("Production", "Services", "Support", "Support", "Services", "Production", "Production", "Support", "Support", "Support", "Production"), times = 5)), 
  revenue = rep(c(100, 200, 300, 400, 500, 600, 500, 400, 300, 200, 500), times = 5)
)

sales_data$month <- factor(sales_data$month, levels = c("Jan", "Feb", "Mar"))
month_vector <- levels(sales_data$month)
number_of_enteries <- nrow(sales_data)

sales_data$month <- as.integer(sales_data$month)

ggplot(sales_data, aes(x = month, y = dept_name)) +
  geom_raster(data = expand.grid(sales_data$month, sales_data$dept_name), 
            aes(x = Var1, y = Var2, width=1, height=1), fill = NA, col = 'gray50', lty = 1) + #default width and height is 1
  geom_point(aes(size = revenue, col = revenue), 
             shape = 16, position = position_jitter(seed = 0), show.legend = F) +
  geom_text_repel(aes(label = revenue), size=4, vjust = 1.6, position = position_jitter(seed = 0)) + #try with geom_text

  theme_bw() +
  theme(
    axis.title = element_blank(),
    axis.ticks = element_blank(),
    plot.background = element_blank(), 
    axis.line = element_blank(), 
    panel.border = element_blank(), 
    panel.grid = element_blank(),
    #panel.grid.major.y = element_line(colour = "red"),
    #panel.grid.major.x = element_line(colour = "red"),
    axis.text = element_text(colour = "blue", face = "plain", size =11)
  ) +

  scale_x_continuous(limits=c(0.5,3.5), expand = c(0,0), breaks = 1:length(month_vector), labels = month_vector)

输出图是：预期图：我希望沿x和y轴有刻度线，如红线所示。我尝试在panel.grid中使用theme，但由于我的自定义添加了scale_x_continuous，它给了我不需要的主要小轴。请取消注释行panel.grid.major.y = element_line(colour = "red"),to，请参阅major网格。

请帮忙。

Answer 1

令人惊讶的是，据我所知，似乎没有一种好方法可以在离散类别之间获得panel.grid线。解决这个问题的一种方法是使用hline和vline添加这些行：

在ggplot代码中，添加以下3行：

# Remove extra whitespace from y-axis so lines are against the axis
scale_y_discrete(expand = c(0,0)) +
# Add straight lines at each factor level, shifted left/down so they're between values
geom_hline(yintercept = as.numeric(sales_data$dept_name) - 0.5) +
geom_vline(xintercept = as.numeric(sales_data$month) - 0.5)