trek function

Grab a trek from Google

Sequence treks (latitude-longitude sequences following ordinary paths, e.g. roads) between two locations using the Google Directions API. Note: To use Google's Directions API, you must first enable the API in the Google Cloud Platform Console. See register_google().

trek(
  from,
  to,
  mode = c("driving", "walking", "bicycling", "transit"),
  output = c("simple", "all"),
  alternatives = FALSE,
  units = "metric",
  urlonly = FALSE,
  override_limit = FALSE,
  ext = "com",
  inject = "",
  ...
)

Arguments

• from: name of origin addresses in a data frame
• to: name of destination addresses in a data frame
• mode: driving, bicycling, walking, or transit
• output: amount of output ("simple" or "all")
• alternatives: should more than one route be provided?
• units: "metric"
• urlonly: return only the url?
• override_limit: override the current query count
• ext: domain extension (e.g. "com", "co.nz")
• inject: character string to add to the url
• ...: ...

Returns

a tibble

Examples

## Not run:
 requires Google API key, see ?register_google

## basic usage
########################################

from <- "houston, texas"
to <- "waco, texas"

(route_df <- route(from, to, structure = "route"))
(trek_df  <-  trek(from, to, structure = "route"))

qmap("college station, texas", zoom = 8) +
  geom_path(
    aes(x = lon, y = lat),  colour = "red",
    size = 1.5, alpha = .5,
    data = route_df, lineend = "round"
  ) +
  geom_path(
    aes(x = lon, y = lat),  colour = "blue",
    size = 1.5, alpha = .5,
    data = trek_df, lineend = "round"
  )


from <- "rice university houston texas"
to <- "1001 Bissonnet St, Houston, TX 77005"
trek_df <- trek(from, to)
qmplot(lon, lat, data = trek_df, geom = "path", maptype = "terrain",
  color = I("red"), size = I(2), alpha = I(.5)
)

trek_df <- trek(from, to, mode = "walking")
qmplot(lon, lat, data = trek_df, geom = "path", maptype = "terrain",
  color = I("red"), size = I(2), alpha = I(.5)
)

trek_df <- trek(from, to, mode = "transit")
qmplot(lon, lat, data = trek_df, geom = "path", maptype = "terrain",
  color = I("red"), size = I(2), alpha = I(.5)
)


## neat faceting example
########################################

from <- "houston, texas"; to <- "waco, texas"
trek_df <- trek(from, to, alternatives = TRUE)

qmplot(lon, lat, data = trek_df, geom = "path",
  color = route, size = I(2), maptype = "terrain",
  alpha = I(.5)
)

qmplot(lon, lat, data = trek_df, geom = "path",
  color = route, size = I(2), maptype = "terrain",
  zoom = 8
) + facet_grid(. ~ route)
## End(Not run)

See Also

https://developers.google.com/maps/documentation/directions/, https://stackoverflow.com/questions/30270011/ggmap-route-finding-doesnt-stay-on-roads/, route(), routeQueryCheck(), register_google()

Author(s)

David Kahle david@kahle.io with the key decoding algorithm due to Stack Overflow user akhmed