lutz (look up timezones)

Input latitude and longitude values or an sf or sfc POINT object and get back the timezone in which they exist. This package uses the V8 package to access the tz-lookup.js javascript library.

Installation

You can install lutz from github with:

# install.packages("devtools")
devtools::install_github("ateucher/lutz")

Example

There are only two functions in this package: tz_lookup() which works with both sf/sfc and SpatialPoints objects, and tz_lookup_coords for looking up lat/long pairs.

With coordinates. They must be lat/long in decimal degrees:

library(lutz)
tz_lookup_coords(49.5, -123.5)
#> [1] "America/Vancouver"

tz_lookup_coords(lat = c(48.9, 38.5, 63.1, -25), lon = c(-123.5, -110.2, -95.0, 130))
#> [1] "America/Vancouver"    "America/Denver"       "America/Rankin_Inlet"
#> [4] "Australia/Darwin"

With sf objects:

library(sf)
library(ggplot2) # this requires the devlopment version of ggplot2

# Create an sf object out of the included state.center dataset:
pts <- lapply(seq_along(state.center$x), function(i) {
  st_point(c(state.center$x[i], state.center$y[i]))
})
state_centers_sf <- st_sf(st_sfc(pts))

# Use tz_lookup_sf to find the timezones
state_centers_sf$tz <- tz_lookup(state_centers_sf)

ggplot() + 
  geom_sf(data = state_centers_sf, aes(colour = tz)) + 
  theme_minimal() + 
  coord_sf(datum = NA)

With SpatialPoints objects:

library(sp)
state_centers_sp <- as(state_centers_sf, "Spatial")

state_centers_sp$tz <- tz_lookup(state_centers_sp)

ggplot(cbind(as.data.frame(coordinates(state_centers_sp)), tz = state_centers_sp$tz), 
       aes(x = coords.x1, y = coords.x2, colour = tz)) + 
  geom_point() + 
  coord_fixed() + 
  theme_minimal()