ddbh3_get_hierarchy: Get parent and children H3 cells

In duckh3: H3 Extension of 'DuckDB'

Get parent and children H3 cells

Description

Get the parent or children H3 cells of H3 cell indexes stored as strings or unsigned 64-bit integers (UBIGINT) at a specified resolution: ddbh3_get_parent(), ddbh3_get_center_child(), ddbh3_get_children(), and ddbh3_get_n_children().

Usage

ddbh3_get_parent(
  x,
  resolution = 8,
  h3 = "h3string",
  new_column = "h3parent",
  conn = NULL,
  name = NULL,
  overwrite = FALSE,
  quiet = FALSE
)

ddbh3_get_children(
  x,
  resolution = 8,
  h3 = "h3string",
  new_column = "h3children",
  conn = NULL,
  name = NULL,
  nested = FALSE,
  overwrite = FALSE,
  quiet = FALSE
)

ddbh3_get_n_children(
  x,
  resolution = 8,
  h3 = "h3string",
  new_column = "h3n_children",
  conn = NULL,
  name = NULL,
  overwrite = FALSE,
  quiet = FALSE
)

ddbh3_get_center_child(
  x,
  resolution = 8,
  h3 = "h3string",
  new_column = "h3center_child",
  conn = NULL,
  name = NULL,
  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).
resolution	A number specifying the resolution level of the H3 string (between 0 and 15)
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
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.
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.

Details

The four functions differ in the type of related cell they retrieve:

• ddbh3_get_parent() returns the parent cell at a coarser resolution

• ddbh3_get_center_child() returns the center child cell at a finer resolution

• ddbh3_get_children() returns all children cells at a finer resolution

• ddbh3_get_n_children() returns the number of children cells at a finer resolution, without computing them

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 strings
points_tbl <- ddbh3_lonlat_to_h3(points_tbl, resolution = 8)

## GET PARENTS ----------

## Get resolution-7 parent
points_parent_tbl <- ddbh3_get_parent(points_tbl, resolution = 7)

## Check the resolution
ddbh3_get_resolution(
  points_parent_tbl,
  h3 = "h3parent"
)

## Add with mutate
points_tbl |> 
  mutate(parent4 = ddbh3_get_parent(h3string, 4))

## GET CHILDREN ----------

## Get level 9 children
children_9_tbl <- ddbh3_get_children(points_tbl, resolution = 9)

## Get level 9 children in a nested list
children_9_nested_tbl <- ddbh3_get_children(points_tbl, resolution = 9, nested = TRUE)

## Add with mutate (nested)
points_tbl |> 
  mutate(children9 = ddbh3_get_children(h3string, 9))

## Add with mutate (unnested)
points_tbl |> 
  mutate(children9 = ddbh3_get_children(h3string, 9)) |> 
  mutate(children9 = unnest(children9))

## GET CENTER CHILD ------

## Get the center child of res 10 (1 child per row)
center_child_10_tbl <- ddbh3_get_center_child(points_tbl, resolution = 10)

## Add with mutate
points_tbl |> 
  mutate(center = ddbh3_get_center_child(h3string, 9))

## NUMBER OF CHILDREN -----

## How many children of level 10 does each level 8 have?
n_children_tbl <- ddbh3_get_n_children(points_tbl, resolution = 10)

## Add with mutate
points_tbl |> 
  mutate(n_children = ddbh3_get_n_children(h3string, 15))

duckh3 documentation built on April 25, 2026, 1:07 a.m.