Create one or more unique location IDs — createLocationID • MazamaCoreUtils

Create a location ID for each longitude/latitude pair using a geohash.

createLocationID(
  longitude = NULL,
  latitude = NULL,
  precision = 10,
  algorithm = c("geohash", "digest"),
  invalidID = as.character(NA)
)

Arguments

longitude: Vector of longitudes in decimal degrees east.
latitude: Vector of latitudes in decimal degrees north.
precision: Precision used when encoding geohashes.
algorithm: Encoding algorithm to use. Only "geohash" is currently supported. "digest" is deprecated and will generate an error.
invalidID: Identifier to use for invalid locations. This can be a character string or NA.

Value

Character vector of location IDs.

Details

Each location ID is unique within a geohash grid cell. The precision argument determines the size of the grid cell. At the equator, approximate grid cell widths are:


precision   maximum grid cell width
        5   ~ 4.9 km
        6   ~ 1.2 km
        7   ~ 153 m
        8   ~ 38 m
        9   ~ 4.8 m
       10   ~ 1.2 m

Invalid locations are assigned the value specified by invalidID, typically NA.

References

https://michaelchirico.github.io/geohashTools/index.html

Examples

longitude <- c(-122.5, 0, NA, -122.5, -122.5)
latitude <- c(47.5, 0, 47.5, NA, 47.5)

createLocationID(longitude, latitude)
#> [1] "c22yhrn5x1" "s000000000" NA           NA           "c22yhrn5x1"
createLocationID(longitude, latitude, precision = 7)
#> [1] "c22yhrn" "s000000" NA        NA        "c22yhrn"
createLocationID(longitude, latitude, invalidID = "bad")
#> [1] "c22yhrn5x1" "s000000000" "bad"        "bad"        "c22yhrn5x1"