calc_densities: Calculate densities In tmaptools: Thematic Map Tools

Description

Transpose quantitative variables to densitiy variables, which are often needed for choroplets. For example, the colors of a population density map should correspond population density counts rather than absolute population numbers.

Usage

 ```1 2 3 4 5 6 7 8``` ```calc_densities( shp, var, target = "metric", total.area = NULL, suffix = NA, drop = TRUE ) ```

Arguments

 `shp` a shape object, i.e., an `sf` object or a `SpatialPolygons(DataFrame)` from the `sp` package. `var` name(s) of a qualtity variable name contained in the `shp` data `target` the target unit, see `approx_areas`. Density values are calculated in `var/target^2`. `total.area` total area size of `shp` in number of target units (defined by `unit`), `approx_areas`. `suffix` character that is appended to the variable names. The resulting names are used as column names of the returned data.frame. By default, `_sq_`, where target corresponds to the target unit, e.g. `_sq_km` `drop` boolean that determines whether an one-column data-frame should be returned as a vector

Value

Vector or data.frame (depending on whether `length(var)==1` with density values.

Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13``` ```if (require(tmap) && packageVersion("tmap") >= "2.0") { data(NLD_muni) NLD_muni_pop_per_km2 <- calc_densities(NLD_muni, target = "km km", var = c("pop_men", "pop_women")) NLD_muni <- sf::st_sf(data.frame(NLD_muni, NLD_muni_pop_per_km2)) tm_shape(NLD_muni) + tm_polygons(c("pop_men_km.2", "pop_women_km.2"), title=expression("Population per " * km^2), style="quantile") + tm_facets(free.scales = FALSE) + tm_layout(panel.show = TRUE, panel.labels=c("Men", "Women")) } ```

Example output

```Loading required package: tmap
```

tmaptools documentation built on Jan. 20, 2021, 1:07 a.m.