Hatching: Draws hatching or crosshatching over a mask on a map

In esviz: Plotting Functions for Climate Science and Services

Draws hatching or crosshatching over a mask on a map

Description

Adds hatching or crosshatching lines over grid cells of a map based on a logical mask. The hatching is applied only to grid cells where the mask is TRUE (or 1). A number of graphical options are available to customize the appearance of the hatching, such as line density, angle, line width, and color. Optionally, crosshatching can be drawn using a second set of lines in the opposite direction. The function assumes that the input mask is a 2D array with dimensions corresponding to latitude (rows) and longitude (columns), and it is designed to be used as a layer over existing map plots (e.g., within a call to VizEquiMap) and does not initiate a plot by itself.

Usage

Hatching(
  hatching_mask,
  lat,
  lon,
  data = NULL,
  hatching_density = 10,
  hatching_angle = 45,
  hatching_color = "#252525",
  hatching_lwd = 0.5,
  hatching_cross = FALSE
)

Arguments

hatching_mask	Logical or binary (0/1) array with two named dimensions: c(latitude, longitude).Hatching is applied to grid cells where 'hatching_mask' is TRUE (or 1). Arrays with dimensions c(longitude, latitude) are also accepted, but the resulting hatching may appear transposed. To ensure correct alignment with the map, provide 'data'. The function will compare the dimension order of 'hatching_mask' and 'data', and automatically transpose 'hatching_mask' if the latitude and longitude dimensions appear to be reversed.
lat	Numeric vector of latitude locations of the cell centers of the grid.
lon	Numeric vector of longitude locations of the cell centers of the grid.
data	Array of the data that the hatching will be drawn over. The array should have named latidude and longitude dimensions. If the dimension order is reversed relative to 'hatching_mask', the mask is automatically transposed. Default is NULL.
hatching_density	The density of shading lines, in lines per inch. A zero value of density means no shading nor filling, whereas negative values and NA suppress shading (and so allow color filling). NULL means that no shading lines are drawn. Default is 10.
hatching_angle	The slope of shading lines, given as an angle in degrees (counter-clockwise). Default is 45.
hatching_color	Color of the hatching lines. Default is "#252525".
hatching_lwd	The line width, a positive number. The interpretation is device-specific, and some devices do not implement line widths less than one. Default is 0.5.
hatching_cross	A logical value indicating crosshatching. If TRUE, adds a second set of lines in the opposite angle. Default is FALSE.

Value

Invisibly returns NULL. The function is intended to be used as an overlay layer (e.g., when called within VizEquiMap()). It draws hatching or crosshatching onto an existing graphics device.

Examples

mask_small <- array(c(TRUE, FALSE, TRUE, FALSE), dim = c(lat = 2, lon = 2))
lat_small <- 1:2
lon_small <- 1:2
image(lon_small, lat_small, matrix(1:4, nrow = 2))
Hatching(hatching_mask = mask_small, lat = lat_small, lon = lon_small,
         hatching_lwd = 2)

esviz documentation built on Feb. 4, 2026, 5:13 p.m.