Creates a tmap-element that draws coordinate grid lines. It serves as a layer that can be drawn anywhere between other layers. By default the coordinate system of the (master) shape object is used, which results in horizontal and vertical lines. Alternatively, grid lines can be reprojected, for instance to latitude longitude coordinates, and hence be curved.
tm_grid(x = NA, y = NA, n.x = NA, n.y = NA, projection = NA,
col = NA, lwd = 1, alpha = NA, labels.size = 0.6,
labels.col = NA, labels.rot = c(0, 0),
labels.format = list(big.mark = ","), labels.margin.x = 0,
labels.margin.y = 0, labels.inside.frame = TRUE)x coordinates for vertical grid lines. If NA, it is specified with a pretty scale and n.x.
y coordinates for horizontal grid lines. If NA, it is specified with a pretty scale and n.y.
preferred number of grid lines for the x axis.
preferred number of grid lines for the y axis.
projection character. If specified, the grid lines are projected accordingly. See set_projection for projection details. Many world maps are projected, but still have latitude longitude ("longlat") grid lines.
color of the grid lines.
line width of the grid lines
alpha transparency of the grid lines. Number between 0 and 1. By default, the alpha transparency of col is taken.
font size of the tick labels
font color of the tick labels
Rotation angles of the labels. Vector of two values: the first is the rotation angle (in degrees) of the tick labels on the x axis and the second is the rotation angle of the tick labels on the y axis. Only 0, 90, 180, and 270 are valid values.
list of formatting options for the grid labels. Parameters are:
Function to specify the labels. It should take a numeric vector, and should return a character vector of the same size. By default it is not specified. If specified, the list items scientific, format, and digits (see below) are not used.
Should the labels be formatted scientifically? If so, square brackets are used, and the format of the numbers is "g". Otherwise, format="f", and text.separator, text.less.than, and text.or.more are used. Also, the numbers are automatically rounded to millions or billions if applicable.
By default, "f", i.e. the standard notation xxx.xxx, is used. If scientific=TRUE then "g", which means that numbers are formatted scientifically, i.e. n.dddE+nn if needed to save space.
Number of digits after the decimal point if format="f", and the number of significant digits otherwise.
Other arguments passed on to formatC
margin between tick labels of x axis and the frame
margin between tick labels of y axis and the frame
Show labels inside the frame?