Dissolve

Draft: written, not yet checked by a person Operation · dissolve

Merges features into one per value of the given fields, or into one shape for everything.

Pitfall. Other attributes are dropped or summarized; decide how before dissolving.

About this operation
Also called	Pairwise Dissolve, merge by attribute, aggregate, union by field
Group	`vector/aggregation`
Checks	`geometry.valid`
Pitfalls	1 listed above
Columbus tool	`vector_op · dissolve`
Notes	Not stated
Status	active
Broader	Not stated
Narrower	Not stated
Related	Not stated

Parameters

Name	Type	Required	Default	Values	Note
`by`	fields	no	Not stated	Not stated	Field or fields to group by; omit to merge everything.

Inputs and outputs

Direction	Name	Type	Geometry	Note
Input	`layer`	vector	Not stated	Not stated
Output	`output`	vector	Not stated	Not stated

In each engine

Engine	Tool	Parameters	Differences
`apache-sedona`	`sedona.sql.ST_Union_Aggr`	`by` An aggregate: dissolve by fields with GROUP BY. `layer` → `geometry`	A Spark SQL function: arguments are columns or column names, run over a Spark DataFrame.
`geopandas`	`geopandas.GeoDataFrame.dissolve`	`by` → `by`	Other columns keep the first row's value per group unless aggfunc says otherwise.
`grass`	`v.dissolve`	`by` → `column` `layer` → `input` `output` → `output`	Without a column it dissolves areas sharing the same category number.
`postgis`	`st_union`	`by` Use the aggregate form with GROUP BY the fields. `layer` → `#1`	Dissolving is the aggregate form, ST_Union(geom) with GROUP BY; the two-argument form unions just two geometries.
`qgis`	`native:dissolve`	`by` → `FIELD` `layer` → `INPUT` `output` → `OUTPUT`	SEPARATE_DISJOINT keeps parts that do not touch as separate features.
`sf`	`sf::st_union`	`by` st_union merges everything into one geometry and drops the attributes; to dissolve by a field, group with aggregate() or dplyr's group_by and summarise. `layer` → `x`	Returns geometry only (an sfc), not a layer with attributes.
`shapely`	`shapely.union_all`	`by` Merges everything into one geometry; group the geometries first to dissolve by field. `layer` → `geometries`	None noted
`terra`	`terra::aggregate`	`by` → `by` `layer` → `x`	On a SpatVector, dissolve = TRUE (the default) merges the shapes of each group; without by, everything becomes one.
`turf-js`	`turf.dissolve`	`by` → `options.propertyName` : One property only. `layer` → `fc`	Polygons only. Turf works on GeoJSON in longitude/latitude (WGS 84); data in another CRS must be reprojected first.
`whiteboxtools`	`Dissolve`	`by` → `field` `layer` → `input` `output` → `output`	None noted

Suggest a fix View source YAML