Helpers for interfacing geohashes with sp/sf objects

These functions smooth the gateway between working with geohashes and geospatial information built for the major geospatial packages in R, sp and sf.

gh_to_sp(geohashes)
gh_to_spdf(...)
gh_to_sf(...)

gh_covering(SP, precision = 6L, minimal = FALSE)

# S3 method for default
gh_to_spdf(geohashes, ...)

# S3 method for data.frame
gh_to_spdf(gh_df, gh_col = 'gh', ...)

Arguments

geohashes	character vector of geohashes to be converted to polygons.
...	Arguments for subsequent methods.
SP	A Spatial object (requires bbox and proj4string methods, and over if minimal is TRUE)
precision	integer specifying the precision of geohashes to use, same as gh_encode
minimal	logical; if FALSE, the output will have all geohashes in the bounding box of SP; if TRUE, any geohashes not intersecting SP will be removed.
gh_df	data.frame which 1) contains a column of geohashes to be converted to polygons and 2) will serve as the data slot of the resultant SpatialPolygonsDataFrame object.
gh_col	character column name saying where the geohashes are stored in gh_df.

Details

gh_to_sp relies on the gh_decode function. Note in particular that this function accepts any length of geohash (geohash-6, geohash-4, etc.) and is agnostic to potential overlap, though duplicates will be caught and excluded.

gh_to_spdf.data.frame will use match.ID = FALSE in the call to SpatialPolygonsDataFrame. Please file an issue if you'd like this to be more flexible.

gh_to_sf is just a wrapper of st_as_sf around gh_to_spdf; as such it requires both sp and sf packages to work.

Value

For gh_to_sp, a SpatialPolygons object.

For gh_to_spdf, a SpatialPolygonsDataFrame object.

For gh_to_sf, a sf object.

Examples

  # get the neighborhood of this geohash in downtown Apia as an sp object
  downtown = '2jtc5x'
  apia_nbhd = unlist(gh_neighbors(downtown))
  apia_sp = gh_to_sp(apia_nbhd)

  # all geohashes covering a random sampling within Apia:
  apia_covering = gh_covering(smp <- sp::spsample(apia_sp, 10L, 'random'))

  apia_sf = gh_to_sf(apia_nbhd)