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Dissolve geometry preserving existing or supplied grouping variables

Source: R/st_dissolve.R
st_dissolve.Rd

st_dissolve() dissolves sf and sfc objects. If the input object is an sf object, any existing grouping variables or added grouping variables passed to the .by parameter are included in the output sf data frame.

Usage

st_dissolve(
  x,
  ...,
  .by = NULL,
  .keep = "nest",
  do_union = TRUE,
  .data_key = "data",
  .dissolve_key = "group.comp.id",
  call = caller_env
)

Arguments

x

A sf or sfc object. If sf object, a grouped data frame is allowed.

...

Arguments passed on to spdep::poly2nb

pl

list of polygons of class extending SpatialPolygons, or an sf or sfc object containing non-empty (multi-)polygon objects

row.names

character vector of region ids to be added to the neighbours list as attribute region.id, default seq(1, nrow(x)); if pl has row.names, they are used instead of the default sequence.

snap

boundary points less than snap distance apart are considered to indicate contiguity; used both to find candidate and actual neighbours for planar geometries, but only actual neighbours for spherical geometries, as spherical spatial indexing itself injects some fuzzyness. If not set, for all SpatialPolygons objects, the default is as before sqrt(.Machine$double.eps), with this value also used for sf objects with no coordinate reference system. For sf objects with a defined coordinate reference system, the default value is 1e-7 for geographical coordinates (approximately 10mm), is 10mm where projected coordinates are in metre units, and is converted from 10mm to the same distance in the units of the coordinates. Should the conversion fail, snap reverts to sqrt(.Machine$double.eps).

queen

if TRUE, a single shared boundary point meets the contiguity condition, if FALSE, more than one shared point is required; note that more than one shared boundary point does not necessarily mean a shared boundary line

useC

default TRUE, doing the work loop in C, may be set to false to revert to R code calling two C functions in an n*k work loop, where k is the average number of candidate neighbours

foundInBox

default NULL using R code or st_intersects() to generate candidate neighbours (using snap= if the geometries are not spherical); if not NULL (for legacy purposes) a list of length (n-1) with integer vectors of candidate neighbours (j > i) (as created by the poly_findInBoxGEOS function in rgeos for clean polygons)

.by

[Experimental]

<tidy-select> Optionally, a selection of columns to group by for just this operation, functioning as an alternative to group_by(). For details and examples, see ?dplyr_by.

.keep

Method for handling attributes for input data. By default ("nest"), input data is converted to a nested list column with the name from .data_key. Any other values

do_union

Use sf::st_union() to dissolve geometry if TRUE (default). Use sf::st_combine() if FALSE.

.data_key

Passed to .data argument of tidyr::nest()

.dissolve_key

Used as the column name for the dissolve grouping variable. x can't have any existing columns with this name.

call

The execution environment of a currently running function, e.g. caller_env(). The function will be mentioned in error messages as the source of the error. See the call argument of abort() for more information.