Get the icosahedron faces of H3 cell indexes — ddbh3_get_icosahedron

Get the icosahedron faces intersected by H3 cell indexes stored as strings or unsigned 64-bit integers (UBIGINT). Each H3 cell maps onto one or more of the 20 faces of the underlying icosahedron used to construct the H3 grid.

Usage

ddbh3_get_icosahedron_faces(
  x,
  h3 = "h3string",
  new_column = "h3faces",
  conn = NULL,
  name = NULL,
  nested = FALSE,
  overwrite = FALSE,
  quiet = FALSE
)

Arguments

x

Input data. One of:

duckspatial_df: A lazy spatial data frame via dbplyr.
sf: A spatial data frame.
tbl_lazy: A lazy data frame from dbplyr.
data.frame: A standard R data frame.
character string: A table or view name in conn.
character vector: A vector of values to operate on in vectorized mode (requires conn = NULL).

h3

The name of a column in x containing the H3 strings or H3 unsigned 64-bit integers (UBIGINT)

new_column

Name of the new column to create on the input data. If NULL, the function will return a vector with the result

conn

A connection object to a DuckDB database. If NULL, the function runs on a temporary DuckDB database.

name

A character string of length one specifying the name of the table, or a character string of length two specifying the schema and table names. If NULL (the default), the function returns the result as an sf object

nested

Logical. If TRUE, children are returned as a nested list column (one row per parent cell). If FALSE (default), the result is unnested so each child cell occupies its own row.

overwrite

Boolean. whether to overwrite the existing table if it exists. Defaults to FALSE. This argument is ignored when name is NULL.

quiet

A logical value. If TRUE, suppresses any informational messages. Defaults to FALSE.

Value

One of the following, depending on the inputs:

tbl_lazy: If x is not spatial.
duckspatial_df: If x is spatial (e.g. an sf or duckspatial_df object).
TRUE (invisibly): If name is provided, a table is created in the connection and TRUE is returned invisibly.
vector: If x is a character vector and conn = NULL, the function operates in vectorized mode, returning a vector of the same length as x.

Examples

## Load needed packages
library(duckh3)
library(dplyr)

## Setup the default connection with h3 and spatial extensions
## This is a mandatory step to use duckh3 functions
ddbh3_default_conn(threads = 1)

## Load example data
points_tbl <- read.csv(
  system.file("extdata/example_pts.csv", package = "duckh3")
)

## Add H3 string column
points_tbl <- ddbh3_lonlat_to_h3(points_tbl, resolution = 6)

## Get faces (unnested)
faces_tbl <- ddbh3_get_icosahedron_faces(points_tbl)

## Get faces (nested)
faces_nested_tbl <- ddbh3_get_icosahedron_faces(points_tbl, nested = TRUE)

## Add using mutate (nested)
points_tbl |> 
  mutate(faces = ddbh3_get_icosahedron_faces(h3string))
#> # Source:   SQL [?? x 7]
#> # Database: DuckDB 1.5.2 [unknown@Linux 6.17.0-1011-azure:R 4.5.3/:memory:]
#>        X    id    lat    lon category h3string        faces    
#>    <int> <int>  <dbl>  <dbl> <chr>    <chr>           <list>   
#>  1     1     1 -43.1   16.2  B        86d02dcc7ffffff <int [1]>
#>  2     2     2  29.2   61.9  C        864221ac7ffffff <int [1]>
#>  3     3     3 -20.7   51.3  C        86a20e8f7ffffff <int [1]>
#>  4     4     4  50.9  -14.0  B        86181c6cfffffff <int [1]>
#>  5     5     5 -57.6    8.71 C        86e6cece7ffffff <int [1]>
#>  6     6     6 -56.2   21.5  B        86e69d237ffffff <int [1]>
#>  7     7     7 -33.7  -17.0  C        86c188077ffffff <int [1]>
#>  8     8     8 -32.7  -31.9  A        86c52b36fffffff <int [1]>
#>  9     9     9  -7.39  39.0  C        867b6b577ffffff <int [1]>
#> 10    10    10  10.0  -89.9  A        866d424afffffff <int [1]>
#> # ℹ more rows

## Add using mutate (unnested)
points_tbl |> 
  mutate(faces = ddbh3_get_icosahedron_faces(h3string)) |> 
  mutate(faces_unnested = unnest(faces))
#> # Source:   SQL [?? x 8]
#> # Database: DuckDB 1.5.2 [unknown@Linux 6.17.0-1011-azure:R 4.5.3/:memory:]
#>        X    id    lat    lon category h3string        faces     faces_unnested
#>    <int> <int>  <dbl>  <dbl> <chr>    <chr>           <list>             <int>
#>  1     1     1 -43.1   16.2  B        86d02dcc7ffffff <int [1]>             13
#>  2     2     2  29.2   61.9  C        864221ac7ffffff <int [1]>              0
#>  3     3     3 -20.7   51.3  C        86a20e8f7ffffff <int [1]>             14
#>  4     4     4  50.9  -14.0  B        86181c6cfffffff <int [1]>              3
#>  5     5     5 -57.6    8.71 C        86e6cece7ffffff <int [1]>             18
#>  6     6     6 -56.2   21.5  B        86e69d237ffffff <int [1]>             18
#>  7     7     7 -33.7  -17.0  C        86c188077ffffff <int [1]>             13
#>  8     8     8 -32.7  -31.9  A        86c52b36fffffff <int [1]>             13
#>  9     9     9  -7.39  39.0  C        867b6b577ffffff <int [1]>              9
#> 10    10    10  10.0  -89.9  A        866d424afffffff <int [1]>             12
#> # ℹ more rows