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Quick thematic map plot

Source: R/qtm.R
qtm.Rd

Draw a thematic map quickly. This function is a convenient wrapper of the main plotting method of stacking tmap-elements. Without arguments or with a search term, this functions draws an interactive map.

Usage

qtm(
  shp = NULL,
  fill = tmap::tm_const(),
  col = tmap::tm_const(),
  size = tmap::tm_const(),
  shape = tmap::tm_const(),
  lwd = tmap::tm_const(),
  lty = tmap::tm_const(),
  fill_alpha = tmap::tm_const(),
  col_alpha = tmap::tm_const(),
  text = tmap::tm_const(),
  text_col = tmap::tm_const(),
  text_size = tmap::tm_const(),
  by = NULL,
  scale = NULL,
  title = NULL,
  crs = NULL,
  bbox = NULL,
  basemaps = NA,
  overlays = NA,
  zindex = NA,
  group = NA,
  group.control = "check",
  style = NULL,
  format = NULL,
  ...
)

Arguments

shp

One of:

  • shape object, which is an object from a class defined by the sf or stars package. Objects from the packages sp and raster are also supported, but discouraged.

  • Not specified, i.e. qtm() is executed. In this case a plain interactive map is shown.

  • An OpenStreetMap search string, e.g. qtm("Amsterdam"). In this case a plain interactive map is shown positioned according to the results of the search query (from OpenStreetMap nominatim)

fill, col, size, shape, lwd, lty, fill_alpha, col_alpha

Visual variables.

text, text_col, text_size

Visual variables.

by

data variable name by which the data is split, or a vector of two variable names to split the data by two variables (where the first is used for the rows and the second for the columns). See also tm_facets().

scale

numeric value that serves as the global scale parameter. All font sizes, symbol sizes, border widths, and line widths are controlled by this value. The parameters symbols.size, text.size, and lines.lwd can be scaled separately with respectively symbols.scale, text.scale, and lines.scale. See also ....

title

main title. For legend titles, use X.legend, where X is the layer name (see ...).

crs

Either a crs object or a character value (PROJ.4 character string). By default, the projection is used that is defined in the shp object itself.

bbox

bounding box. Argument passed on to tm_shape()

basemaps

name(s) of the provider or an URL of a tiled basemap. It is a shortcut to tm_basemap(). Set to NULL to disable basemaps. By default, it is set to the tmap option basemaps.

overlays

name(s) of the provider or an URL of a tiled overlay map. It is a shortcut to tm_tiles().

zindex

zindex

group

group

group.control

group.control

style

Layout options (see tm_layout()) that define the style. See tmap_style() for details.

format

Deprecated, see tm_format() for alternatives

...

arguments associated with the visual variables are passed on to the layer functions tm_polygons(), tm_lines(), tm_symbols(), and tm_text(). For instance, fill.scale is the scale specifications of the fill color of polygons (see tm_polygons()).

Value

A tmap-element

Details

The first argument is a shape object (normally specified by tm_shape()). The next arguments, from fill to raster, are the aesthetics from the main layers. The remaining arguments are related to the map layout. Any argument from any main layer function, such as tm_polygons(), can be specified (see ...). It is also possible to stack tmap-elements on a qtm plot. See examples.

By default, a scale bar is shown. This option can be set with tmap_options() (argument qtm.scalebar). A minimap is shown by default when qtm is called without arguments of with a search term. This option can be set with tmap_options() (argument qtm.minimap).

References

Tennekes, M., 2018, tmap: Thematic Maps in R, Journal of Statistical Software, 84(6), 1-39, doi:10.18637/jss.v084.i06

Examples

data(World, World_rivers, metro)

# just the map
qtm(World)
#> [tip] Consider a suitable map projection, e.g. by adding `+ tm_crs("auto")`.
#> This message is displayed once per session.


# choropleth
qtm(World, fill = "economy", style = "cobalt", crs = "+proj=eck4")


qtm(World, col = NULL) +
qtm(metro, size = "pop2010",
  size.legend = tm_legend("Metropolitan Areas"))


# dot map
if (FALSE) { # \dontrun{
current.mode <- tmap_mode("view")
qtm(metro, bbox = "China")
tmap_mode(current.mode) # restore mode
} # }

if (FALSE) { # \dontrun{
# without arguments, a plain interactive map is shown (the mode is set to view)
qtm()

# search query for OpenStreetMap nominatim
qtm("Amsterdam")
} # }