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Set upper and lower limits for geom_area() in ggplot2

Time:03-01

I plotted geom_line() and geom_hline() for date and fb columns in df:

df <- structure(list(date = c("2015-5-1", "2015-6-1", "2015-7-1", "2015-8-1", 
"2015-9-1", "2015-10-1", "2015-11-1", "2015-12-1", "2016-1-1", 
"2016-2-1", "2016-3-1", "2016-4-1", "2016-5-1", "2016-6-1", "2016-7-1", 
"2016-8-1", "2016-9-1", "2016-10-1"), fb = c(8.055790592, 8.032818097, 
8.005365822, 7.985498773, 7.959200396, 7.919847621, 7.877668588, 
7.835635821, 7.804472389, 7.788280201, 7.772438537, 7.750286446, 
7.720577645, 7.699622927, 7.679943452, 7.671596434, 7.678374461, 
7.677040934), ab = c(14.79734541, 14.66345424, 14.52954117, 14.39551705, 
14.2613928, 14.12742798, 13.99331597, 13.85911943, 13.7250579, 
13.59078964, 13.45659479, 13.32220287, 13.18777806, 13.05347518, 
12.91905494, 12.78450571, 12.65039408, 12.51588272)), class = "data.frame", row.names = c(NA, 
-18L))


df1 <- df %>% 
  mutate_at(vars(-date), funs(./100))
df1 %>% 
  ggplot(aes(x=as.POSIXct(date), y=fb))   
  geom_line(size=1, alpha=0.7, color='red')  
  # geom_area(fill='red', alpha=0.3, position = "identity")  
  geom_hline(yintercept=c(min(df1$fb), max(df1$fb)), linetype='solid', col='black')

enter image description here

I filled area using geom_area(fill='red', alpha=0.3, position = "identity"), but as you may notice, the area starting from df1$fb == 0 which generate a large futile areas (areas in the blue rectangle as shown in the figure below).

df1 %>% 
  ggplot(aes(x=as.POSIXct(date), y=fb))   
  geom_line(size=1, alpha=0.7, color='red')  
  geom_area(fill='red', alpha=0.3, position = "identity")  
  geom_hline(yintercept=c(min(df1$fb), max(df1$fb)), linetype='solid', col='black')

enter image description here

So my question is how could we only fill the underline area between minimum and maximum values of fb? Thanks for your help at advance.

CodePudding user response:

geom_area is a special case of geom_ribbon which starts at 0. Use geom_ribbon and specify ymin and y:

df1 %>% 
  ggplot(aes(x=as.POSIXct(date), y=fb))   
  geom_line(size=1, alpha=0.7, color='red')  
  geom_ribbon(aes(ymin = min(fb), ymax = fb), fill = 'red', alpha=0.3, position = "identity")  
  geom_hline(yintercept=c(min(df1$fb), max(df1$fb)), linetype='solid', col='black')

enter image description here

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