Alternative image function

Source: R/image2.R

Creates a grid of colored or gray-scale rectangles. This function is similar to graphics::image() when used for a matrix but simpler (i.e less available features).

image2(
  x,
  from = NULL,
  to = NULL,
  color_scale = NULL,
  border = NA,
  add_value = FALSE,
  val_cex = 1,
  n_signif = 2,
  ...
)

Arguments

x

a matrix or an object to be coerced as a matrix.
from

matrix values equal to or smaller than from will be associated with the first color of the color scale.
to

values equal to or larger than from will be associated with the last color of the color scale.
color_scale

a vector of colors.
border

color for rectangle borders (see graphics::rect()).
add_value

a logical should value be added in the middle of the rectangles drawn?
val_cex

coefficient of magnification used if values are displayed.
n_signif

number of significant numbers to be displayed (used when labelc is NULL).
...

further arguments to be passed to graphics::rect().

Details

This function actually draws rectangles to create an image from a matrix. Unlike graphics::image(), image2 the image is ordered just as the matrix is displayed meaning that the cell (1,1) is at the upper left cell of the plot drawn. Note that currently neither titles nor axes' labels are added user should call the graphics::title() and graphics::axis(). Concerning the latter, the user should be aware that cell's coordinates range from 0 to 1 with 0 being the coordinates of the first cell and 1 the coordinates of the last cell (if there is only one cell then the center of the unique cell is 0).

See also

graphics::image() graphics::rect()

Examples

image2(matrix(1:9, 3))

image2(matrix(1:9, 3), add_value = TRUE)

image2(matrix(1:27, 3), from=2, border = 2, lwd=2)