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Quick map

Source: R/qmap.R
qmap.Rd

qmap is a shortcut similar to ggplot2's qplot designed to quickly plot data with a limited range of options.

Usage

qmap(
  data,
  ...,
  x = NULL,
  y = NULL,
  geom = "point",
  limits = NULL,
  shapefiles = NULL,
  crs = NULL,
  bathymetry = FALSE,
  glaciers = FALSE,
  rotate = FALSE,
  legends = TRUE,
  legend.position = "right",
  lon.interval = NULL,
  lat.interval = NULL,
  bathy.style = NULL,
  downsample = 0,
  bathy.border.col = NA,
  bathy.size = 0.1,
  bathy.alpha = 1,
  land.col = "grey60",
  land.border.col = "black",
  land.size = 0.1,
  gla.col = "grey95",
  gla.border.col = "black",
  gla.size = 0.1,
  grid.col = "grey70",
  grid.size = 0.1,
  base_size = 11,
  projection.grid = FALSE,
  expand.factor = 1.1,
  verbose = FALSE
)

Arguments

data

Data frame to use.

x, y, ...

Aesthetics passed into each layer. Longitude and latitude columns are automatically recognized using the guess_coordinate_columns function.

geom

Character argument specifying geom(s) to draw. Defaults to "point". Other alternatives are "text" and "label". The "text" option can also be triggered by simply mapping a variable to label (see Examples).

limits

Map limits. One of the following:

  • numeric vector of length 4: The first element defines the start longitude, the second element the end longitude (counter-clockwise), the third element the minimum latitude, and the fourth element the maximum latitude of the bounding box. Also accepts sf::st_bbox type named vectors with limits in any order. The coordinates can be given as decimal degrees or coordinate units for shapefiles used by a projected map. Produces a rectangular map. Latitude limits not given in min-max order are automatically ordered to respect this requirement.

  • single integer between 30 and 88 or -88 and -30 produces a polar map for the Arctic or Antarctic, respectively.

Can be omitted if data or shapefiles are defined.

shapefiles

Either a list containing shapefile information or a character argument referring to a name of pre-made shapefiles in shapefile_list. This name is partially matched. Can be omitted if limits or data is defined as decimal degrees.

crs

Coordinate reference system (CRS) for the map. If NULL (default), the CRS is selected automatically based on limits, data, or shapefiles. Passed to st_crs. Typically integers giving the EPGS code are the easiest. Cannot be used simultaneously with rotate.

bathymetry

Logical indicating whether bathymetry should be added to the map. Functions together with bathy.style. See Details.

glaciers

Logical indicating whether glaciers and ice sheets should be added to the map.

rotate

Logical indicating whether the projected maps should be rotated to point towards the pole relative to the mid-longitude limit.

legends

Logical indicating whether the legend for bathymetry should be shown.

legend.position

The position for ggplot2 legend. See the argument with the same name in theme.

lon.interval, lat.interval

Numeric value specifying the interval of longitude and latitude grids. NULL finds reasonable defaults depending on limits.

bathy.style

Character (plots bathymetry; list of alternatives in Details) or NULL ("raster_binned_blues" if bathymetry = TRUE) defining the bathymetry style. Partially matched, can be abbreviated, and used to control bathymetry plotting together with bathymetry. See Details.

downsample

Integer defining the downsampling rate for raster bathymetries. A value of 0 (default) does not downsample, 1 skips every second row, 2 every second and third. See geom_stars

bathy.alpha

Transparency parameter for the bathymetry fill color. See scale_alpha.

land.col, gla.col, grid.col

Character code specifying the color of land, glaciers, and grid lines, respectively. Use NA to remove the grid lines.

land.border.col, gla.border.col, bathy.border.col

Character code specifying the color of the border line for land, glacier, and bathymetry shapes.

land.size, gla.size, bathy.size, grid.size

Numeric value specifying the width of the border line land, glacier and bathymetry shapes as well as the grid lines, respectively. Use the LS function for a specific width in pt. See Details.

base_size

Base size parameter for ggplot. See ggtheme.

projection.grid

Logical indicating whether the coordinate grid should show projected coordinates instead of decimal degree values. Useful to define limits for large maps in polar regions.

expand.factor

Expansion factor for map limits. Can be used to zoom in (decrease the value under 1) and out (increase the value over 1) automatically (data) limited maps. Defaults to 1, which means that outermost data points are located at the boundaries of the plotting region.

verbose

Logical indicating whether information about the projection and guessed column names should be returned as messages. Set to FALSE to make the function silent.

Value

Returns a ggplot map, which can be assigned to an object and modified as any ggplot object.

See also

Other basemap functions: basemap(), shapefile_list(), transform_coord()

Author

Mikko Vihtakari

Examples

dt <- data.frame(lon = c(-100, -80, -60), lat = c(10, 25, 40), var = c("a", "a", "b"))

# Quickly see position of data
qmap(dt)


# \donttest{
# Set color
qmap(dt, color = I("blue")) 


# Map color to a variable
qmap(dt, color = var) 

 
# Map text to a variable 
qmap(dt, label = var) 


# All basemap arguments work in qmap()
dt <- data.frame(lon = c(-80, -80, -50, -50), lat = c(65, 80, 80, 65))
qmap(dt, rotate = TRUE)

# }