From dusk till dawn

In gghourglass: Plot Records per Time of Day

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "man/figures/timezones-",
  fig.ext = "png",
  dev = "png")
tryCatch({
  Sys.setlocale("LC_ALL", "English")
})
library(ggplot2)
theme_set(theme_light())

This vignette presents some vital aspects of decorating your plot with solar cylce information

## load required namespaces for this vignette
library(ggplot2)
library(gghourglass)

With annotate_daylight() you can add ribbons to your plot reflecting the solar cycle. By default, it marks the time between sunset and sunrise:

## get example data
data(bats)

## subset example date to the year 2018
bats_sub <- subset(bats, format(RECDATETIME, "%Y") == "2019")

## retrieve monitoring location
lon <- attr(bats, "monitoring")$longitude[1]
lat <- attr(bats, "monitoring")$latitude[1]

## plot the data
p <- ggplot(bats_sub, aes(x = RECDATETIME)) +

    ## add hourglass geometry to plot
    geom_hourglass() +

    ## add informative labels
    labs(x = "Date", y = "Time of day")

## decorate the plot with night time ribbon
p + annotate_daylight(lon, lat, c("sunset", "sunrise"), fill = "darkblue")

The order in which you include the solar events matter. In the example above, the time between sunset and sunrise (i.e., night time) is marked with a dark blue ribbon. But if you reverse the order, it will mark the day time:

p + annotate_daylight(lon, lat, c("sunrise", "sunset"), fill = "orange")

Moreover, you are not bound to only sunrise and sunset. You can pick any of the events supported by the suncalc package:

" * " |>
  paste0(
    formals(suncalc::getSunlightTimes)$keep |>
      eval()) |>
  paste0(collapse = "\n") |>
  cat()

gghourglass documentation built on April 11, 2025, 5:53 p.m.