area_plot_in_base_graphics.R

area_plot_in_base_graphics.R

# How to fill area under the line in base graphics
  library(xts)
  library(data.table)
  library(lubridate)
  set.seed(100)
  date_seq <- seq.POSIXt(from=ymd("2016-01-01", tz="UTC"), length=100, by = "day")
  y <- round(runif(100), 2)
  df <- data.table(date=date_seq, y)
  head(df)
  
  # Convert to xts obj, so X-axis has dates.
  df_xts <- as.xts(df)
  
  # Get X and Y 
  x <- df$date
  y <- as.numeric(df_xts$y)
  
  # Plot it
  plot(df_xts$y, cex.axis=0.4, main="Area plots with polygon()")
  polygon(c(min(x), x, max(x)), c(0, y, 0), col=rgb(0, 1, 0, 0.7))