Make Google Traffic PNG — gt_make

Make a png file of Google traffic data. The gt_load_png_as_traffic_raster() function can then be used to convert the png into a traffic raster

Usage

gt_make_png(
  location,
  height,
  width,
  zoom,
  out_filename,
  google_key,
  webshot_zoom = 1,
  webshot_delay = NULL,
  print_progress = TRUE
)

Arguments

location: Vector of latitude and longitude
height: Height (in pixels; pixel length depends on zoom)
width: Width (in pixels; pixel length depends on zoom)
zoom: Zoom level; integer from 5 to 20. For more information about how zoom levels correspond to pixel size, see here and here.
out_filename: Filename of PNG file to make
google_key: Google API key, where the Maps JavaScript API is enabled. To create a Google API key, follow these instructions.
webshot_zoom: How many pixels should be created relative to height and width values. If height and width are set to 100 and webshot_zoom is set to 2, the resulting raster will have dimensions of about 200x200 (default: 1).
webshot_delay: How long to wait for Google traffic layer to render. Larger height/widths require longer delay times. If NULL, the following delay time (in seconds) is used: delay = max(height,width)/200.
print_progress: Whether to print function progress (default: TRUE)

Value

Returns a PNG file showing traffic levels.

References

Markus Hilpert, Jenni A. Shearston, Jemaleddin Cole, Steven N. Chillrud, and Micaela E. Martinez. Acquisition and analysis of crowd-sourced traffic data. CoRR, abs/2105.12235, 2021.

Pavel Pokorny. Determining traffic levels in cities using google maps. In 2017 Fourth International Conference on Mathematics and Computers in Sciences and in Industry (MCSI), pages 144–147, 2017.

Examples

if (FALSE) {
gt_make_png(location     = c(40.712778, -74.006111),
            height       = 1000,
            width        = 1000,
            zoom         = 16,
            out_filename = "google_traffic.png",
            google_key   = "GOOGLE-KEY-HERE")
}