Make geom_line dotted for forecasted numbers-CodePudding

I have a data.table that I want to plot

cbo = data.table(date = seq(as.Date("2000/4/2"), by = "week", length.out = 9), week = 1:9, x= sample(10000:50000, 9))

Week 6 to 9 forecasts. I want a dotted line from 2000-05-07 onward to signify the forecasts and shade the background in blue.

My ggplot2

ggplot(cbo)  
  aes(x = date, y = x)  
  geom_line(size = 0.5, colour = "#112446")  
  theme_minimal()

Question: How do I dot the line from week == 6, date = 2000-05-07 and shade background in blue colour to distinguish the forecasted numbers?

CodePudding user response：

I think this should accomplish what you're looking to do. I used geom_rect to shade the plot and an ifelse to adjust the linetype in the aes of geom_segment. If you just use geom_line you'll end up with a gap between the dates for week 5 and 6.

library(ggplot2)
library(data.table)

# make data
cbo <- data.table(date = seq(as.Date("2000/4/2"), by = "week", length.out = 9), week = 1:9, x= sample(10000:50000, 9))

# plot data
ggplot(cbo)   
  geom_segment(aes(x = date, xend = lead(date), y = x, yend = lead(x), 
               linetype = ifelse(date > as.Date("2000-04-30"), "solid", "dashed")), # adjust linetype
               size = 1)  
  # plot a rectangle
  geom_rect(aes(xmin = as.Date("2000-05-07"), xmax = as.Date("2000-05-30"), ymin = min(x), ymax = Inf), 
            fill = "blue", alpha = 0.1)  # adjust alpha for shading
  theme_minimal()   
  theme(legend.position = 'none')

CodePudding user response：

You can plot geom_line twice. Once with a solid line until week 6 and once with a dotted line for the whole line.

library(tidyverse)
library(data.table)

cbo = data.table(date = seq(as.Date("2000/4/2"), by = "week", length.out = 9), week = 1:9, x= sample(10000:50000, 9))

ggplot(cbo)  
  aes(x = date, y = x)  
  geom_rect(aes(xmin = as.Date("2000-05-07"), xmax = as.Date("2000-05-28"), ymin = -Inf, ymax = Inf),
        fill = "#6BC6F5FF", alpha = 0.1)  
  geom_line(size = 0.5, colour = "#112446", lty = 2)  
  geom_line(data = cbo %>% filter(week <= 6), size = 0.7, color = "#112446", lty = 1)  
  theme_minimal()