This vignette summarizes the main changes in tmap 2.x/3.x in comparison to tmap 1.11-2, which is described in detail in the JSS paper. The code of this paper for version 2.x/3.x can be found in
For people who are new to tmap, see
As of version 2.0, all tmap functions have the prefix
tmap_, with the exception of the function
qtm. Just like in tmap version 1.x, the layer functions start with
tm_. In tmap 1.x, the names of the other functions where inconsistent, e.g.
tmap_arrange. In tmap 2.x/3.x, these functions are prefixed with
tmap_. For instance
animation_tmap has been renamed to
tmap 1.x uses
sp for representing vector data, and
raster for raster data. tmap 2.x uses
sf for representing vector data, and
raster for raster data. tmap 3.x uses
sf for representing vector data, and
stars for raster data.
sf (simple features) objects have a simpler structure than
sp objects. An
sf object is nothing more than a
data.frame with a special geometry column that contains the geometries for the corresponding rows. Such a geometry can be of type spatial point(s), line(s) or polygon(s) or any combination of these in a ‘geometrycollection’ (see
vignette("sf1")). The layers functions, such as
tm_polygons, will only draw what they are supposed to draw (in this case polygons). The newly added layer function
tm_sf will draw all geometries.
Finally, all data objects in
land) have been transformed into
sf objects. The object
land has been transformed into a
Layer functions have been added to facilitate tile layers. In version 1.x, it was already possible to add basemaps. In version 2.0, this is facilitated by the explicit layer functions
tm_tiles. The former creates a basemap tile and the latter an overlay tile. The difference is that
tm_basemap layers are always drawn at the bottom, whereas the plotting order of (overlay)
tm_tiles layers is derived from the plot call. Overlay layers should be semi-transparent to be useful.
Tip: all tilemaps from https://leaflet-extras.github.io/leaflet-providers/preview/ can be used. The names of these maps can also be found in the list object
data(World, metro) tmap_mode("view") tm_basemap(leaflet::providers$CartoDB.PositronNoLabels, group = "CartoDB basemap") + tm_shape(World) + tm_polygons("HPI", group = "Countries") + tm_tiles(leaflet::providers$CartoDB.PositronOnlyLabels, group = "CartoDB labels") + tm_shape(metro) + tm_dots(col = "red", group = "Metropolitan areas")
There are many options in tmap. In version 1.x, the default values were stored in
tm_view. Wrapper functions like
tm_format_World where used to change these options.
In version 2.0, the options are stored in a similar fashion to the global options. A list of tmap options can be retrieved and options can be set with the function
tmap_options. Its behavior is similar to the base function
A style is a configuration of the options used to style a map in a specific way. When set with
tmap_style, the current options are overwritten according to the new style. The changes can be seen with
tmap_options_diff and can be reset with
tmap_options_diff() ## current tmap options (style "classic") that are different from default tmap options (style "white"): ## $sepia.intensity ##  0.7 ## ## $frame.double.line ##  TRUE ## ## $fontfamily ##  "serif" ## ## $compass.type ##  "rose" ## ## $basemaps ##  "Esri.WorldTopoMap" ## ## $basemaps.alpha ##  0.5 tmap_options_reset() ## tmap options successfully reset
Styles included in tmap are:
"classic". New styles can saved and loaded with
In version 1.x,
tmap contained a couple of predefined format functions, such as
tm_format_World. In version 2.0, these have been replaced by the general function
tm_format. With this function, the available formats can be retrieved, as well as the configuration of a specific format. With the function
tm_format_add new formats can be created.
tmap_format() ## available formats are: "World", "World_wide", "NLD", "NLD_wide" panorama <- tmap_format("World") panorama$asp <- 6 tmap_format_add(panorama, name = "panorama") ## format panorama succesfully added. Use this format with tm_format("panorama") tmap_format() ## available formats are: "World", "World_wide", "NLD", "NLD_wide", "panorama"
Unlike a style, a format cannot be set globally. Instead, it has to be specified in each plot:
Viridis palettes (from the
viridisLite package) are supported natively. E.g.
qtm(World, "HPI", fill.palette = "-plasma"). Notice that, like with the color brewer palette names, a minus sign will reverse the palette. See
tmaptools::palette_explorer() to explore the color brewer and viridis palettes interactively.
The arguments that define the color palette mapping has been made more intuitive. The newly added layer function arguments
stretch.palettedetermines whether a palette is stretched out when there are more categories than available colors. If set to
FALSE, the palette is repeated.
midpointdetermines which value should be mapped to the middle (neutral) color of the diverging color palette. By default, it is set to 0 if there are positive and negative values. This could mean that only a part of the color palette is used, e.g. when the value range is [-5, 20] and the palette is
"RdBu", the colors will range from light red (-5) to white (0) to dark blue (20). If there are only positive or only negative values, the full palette is shown.
midpointhas been specified, the palette is regarded as a diverging palette, with the middle color interpreted as the neutral color.
The argument filter has been added to
tm_shape. Features that are included will be visualized as usual. Excluded features will still be visualized but without color being mapped. Instead, they will be colored with
colorNULL, a new argument of the layer functions. Note the difference with
colorNA, which is used to color features with missing data.
To show the potiential of this filter the following code chunk creates a map in which only European countries are colored:
Countries outside Europe are colored with
colorNULL, which is
grey95 by default. It can be adjusted in the layer functions, such as
tm_polygons, and in
There are also missing values in the data (Kosovo and Moldova) which are colored with the
colorNA (by default