Scales in tmap are configured by the family of functions with prefix `tm_scale`. Such function should be used for the input of the `.scale` arguments in the layer functions (e.g. `fill.scale` in [tm_polygons()]). The function `tm_scale_composition()` is used for the creation of composition glyphs, such as pie charts and donut charts.
Usage
tm_scale_composition(
values = NA,
values.repeat = FALSE,
values.range = NA,
values.scale = 1,
value.na = NA,
value.null = NA,
value.neutral = NA,
labels = NULL,
label.na = NA,
label.null = NA
)Arguments
- values
(generic scale argument) The visual values. For colors (e.g. `fill` or `col` for `tm_polygons()`) this is a palette name from the `cols4all` package (see [cols4all::c4a()]) or vector of colors, for size (e.g. `size` for `tm_symbols()`) these are a set of sizes (if two values are specified they are interpret as range), for symbol shapes (e.g. `shape` for [tm_symbols()]) these are a set of symbols, etc. The tmap option `values.var` contains the default values per visual variable and in some cases also per data type.
- values.repeat
(generic scale argument) Should the values be repeated in case there are more categories?
- values.range
(generic scale argument) Range of the values. Vector of two numbers (both between 0 and 1) where the first determines the minimum and the second the maximum. Full range, which means that all values are used, is encoded as `c(0, 1)`. For instance, when a grey scale is used for color (from black to white), `c(0,1)` means that all colors are used, `0.25, 0.75` means that only colors from dark grey to light grey are used (more precisely `"grey25"` to `"grey75"`), and `0, 0.5` means that only colors are used from black to middle grey (`"grey50"`). When only one number is specified, this is interpreted as the second number (where the first is set to 0). Default values can be set via the tmap option `values.range`.
- values.scale
(generic scale argument) Scaling of the values. Only useful for size-related visual variables, such as `size` of [tm_symbols()] and `lwd` of [tm_lines()].
- value.na
(generic scale argument) Value used for missing values. See tmap option `"value.na"` for defaults per visual variable.
- value.null
(generic scale argument) Value used for NULL values. See tmap option `"value.null"` for defaults per visual variable. Null data values occur when out-of-scope features are shown (e.g. for a map of Europe showing a data variable per country, the null values are applied to countries outside Europe).
- value.neutral
(generic scale argument) Value that can be considered neutral. This is used for legends of other visual variables of the same map layer. E.g. when both `fill` and `size` are used for [tm_symbols()] (using filled circles), the size legend items are filled with the `value.neutral` color from the `fill.scale` scale, and fill legend items are bubbles of size `value.neutral` from the `size.scale` scale.
- labels
(generic scale argument) Labels
- label.na
(generic scale argument) Label for missing values
- label.null
(generic scale argument) Label for null (out-of-scope) values