Unix-style Filters for H3

The directory src/apps/filters contains unix-style stdin/stdout filters that perform conversions between integer H3 indexes and other useful types. It currently contains the filters listed in the table below. See the header comments in each application source code file for more information.

Filters are experimental and are not part of the semantic version of the H3 library.

All latitude/longitude coordinates are in decimal degrees. See the H3 Index Representations page for information on the integer H3Index.

filter	input	outputs
latLngToCell	lat/lng	H3Index
cellToLatLng	H3Index	cell center point in lat/lng
cellToBoundary	H3Index	cell boundary in lat/lng
h3ToComponents	H3Index	components
gridDisk	H3Index	surrounding H3Index
gridDiskUnsafe	H3Index	surrounding H3Index, in order

Unix Command Line Examples

• find the index for coordinates at resolution 5

  latLngToCell --resolution 5 --latitude 40.689167 --longitude -74.044444

• output the cell center point for H3Index 845ad1bffffffff

  cellToLatLng --index 845ad1bffffffff

• output the cell boundary for H3Index 845ad1bffffffff

  cellToBoundary --index 845ad1bffffffff

• find the components for the H3Index 845ad1bffffffff

  h3ToComponents --index 845ad1bffffffff

• output all indexes within distance 1 of the H3Index 845ad1bffffffff

  kRing -k 1 --origin 845ad1bffffffff

• output all hexagon indexes within distance 2 of the H3Index 845ad1bffffffff

  hexRange -k 2 --origin 845ad1bffffffff

Note that the filters cellToLatLng and cellToBoundary take optional arguments that allow them to generate kml output. See the header comments in the corresponding source code files for details.