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Pycnophylactic interpolation to an ISEA grid

Source: R/to_isea.R
to_isea.Rd

Interpolates polygon counts to an ISEA discrete global grid while preserving source-zone totals.

Usage

to_isea(source, value_col, resolution, aperture = c(3, 4), ...)

Arguments

source

An sf polygon object in a projected CRS.

value_col

Column containing the values to interpolate. May be supplied as an unquoted column name or a character string.

resolution

ISEA resolution level. Higher values produce smaller cells and substantially more output polygons.

aperture

ISEA aperture: one of 3 or 4.

...

Additional arguments passed to to_grid().

Value

An sf object containing ISEA cells and interpolated values.

Details

ISEA grids are equal-area hierarchical discrete global grid systems based on the Icosahedral Snyder Equal Area projection. The aperture determines the refinement factor between successive resolutions: aperture 3, 4, or 7.

Calls to_grid() with grid_type set to "isea3h" or "isea4h" according to aperture.

Examples

out <- to_isea(
  source = nyc_ct_small,
  value_col = populationE,
  resolution = 18,
  aperture = 3,
  max_iter = 5
)
#> Warning: Pycnophylactic smoothing did not converge within `max_iter = 5`. Final relative mean change was 0.001357.

out <- to_isea(
  source = nyc_ct_small,
  value_col = populationE,
  resolution = 14,
  aperture = 4,
  max_iter = 5
)
#> Warning: Pycnophylactic smoothing did not converge within `max_iter = 5`. Final relative mean change was 0.0002818.