simplify_shape {tmaptools}

Simplify shape

Description

Simplify a shape consisting of polygons or lines. This can be useful for shapes that are too detailed for visualization, especially along natural borders such as coastlines and rivers. The number of coordinates is reduced.

Usage

simplify_shape(shp, fact = 0.1, keep.units = FALSE, keep.subunits = FALSE, ...)

Arguments

shp

an sf or sfc object.

fact

simplification factor, number between 0 and 1 (default is 0.1)

keep.units

prevent small polygon features from disappearing at high simplification (default FALSE)

keep.subunits

should multipart polygons be converted to singlepart polygons? This prevents small shapes from disappearing during simplification if keep.units = TRUE. Default FALSE

...

other arguments passed on to the underlying function ms_simplify (except for the arguments input, keep, keep_shapes and explode)

Details

This function is a wrapper of ms_simplify. In addition, the data is preserved. Also sf objects are supported.

Value

sf object

Examples

## Not run: 
if (require(tmap)) {
    data(World)

    # show different simplification factors
    tm1 <- qtm(World %>% simplify_shape(fact = 0.05), title="Simplify 0.05")
    tm2 <- qtm(World %>% simplify_shape(fact = 0.1), title="Simplify 0.1")
    tm3 <- qtm(World %>% simplify_shape(fact = 0.2), title="Simplify 0.2")
    tm4 <- qtm(World %>% simplify_shape(fact = 0.5), title="Simplify 0.5")
    tmap_arrange(tm1, tm2, tm3, tm4)

    # show different options for keeping smaller (sub)units
    tm5 <- qtm(World %>% simplify_shape(keep.units = TRUE, keep.subunits = TRUE),
        title="Keep units and subunits")
    tm6 <- qtm(World %>% simplify_shape(keep.units = TRUE, keep.subunits = FALSE),
        title="Keep units, ignore small subunits")
    tm7 <- qtm(World %>% simplify_shape(keep.units = FALSE),
        title="Ignore small units and subunits")
    tmap_arrange(tm5, tm6, tm7)
}

## End(Not run)