| image-methods {Matrix} | R Documentation |
Methods for function image in package
Matrix. An image of a matrix simply color codes all matrix
entries and draws the n x m matrix using an
n x m grid of (colored) rectangles.
## S4 method for signature 'dgTMatrix':
image(x,
xlim = .5 + c(0, di[2]),
ylim = .5 + c(di[1], 0), aspect = "iso",
sub = sprintf("Dimensions: %d x %d", di[1], di[2]),
xlab = "Column", ylab = "Row",
useAbs = NULL, colorkey = !useAbs,
col.regions = NULL,
lwd = NULL, ...)
x |
a Matrix object, i.e., fulfilling
is(x, "Matrix"). |
xlim, ylim |
x- and y-axis limits; may be used to “zoom into” matrix. |
aspect |
aspect ratio specified as number (y/x) or string;
see levelplot. |
sub, xlab, ylab |
axis annotation with sensible defaults;
see plot.default. |
useAbs |
logical indicating if abs(x) should be
shown; if TRUE, the former (implicit) default, the default
col.regions will be grey colors (and no
colorkey drawn). The default is FALSE unless the
matrix has no negative entries. |
colorkey |
logical indicating if a color key aka ‘legend’
should be produced. Default is to draw one, unless useAbs is
true. |
col.regions |
vector of gradually varying colors; see
levelplot. |
lwd |
non-negative number or NULL (default), specifying the
line-width of the rectangles of each non-zero matrix entry (drawn by
grid.rect). The default depends on the matrix
dimension and the device size. |
... |
further arguments passed to methods and
levelplot. |
All methods currently end up calling the method for the
dgTMatrix class.
Use showMethods(image) to list them all.
showMethods(image)
## If you want to see all the methods' implementations:
showMethods(image, incl=TRUE, inherit=FALSE)
data(CAex)
image(CAex, main = "image(CAex)")
image(CAex, useAbs=TRUE, main = "image(CAex, useAbs=TRUE)")
cCA <- Cholesky(crossprod(CAex), Imult = .01)
image(cCA, main="Cholesky(crossprod(CAex), Imult = .01)")
image(cCA, useAbs=TRUE)
data(USCounties)
image(USCounties)# huge
image(sign(USCounties))## just the pattern
# how the result looks, may depend heavily on
# the device, screen resolution, antialiasing etc
# e.g. x11(type="Xlib") may show very differently than cairo-based
## Drawing borders around each rectangle;
# again, viewing depends very much on the device:
image(USCounties[1:400,1:200], lwd=.1)
image(USCounties[1:200,1:200], lwd=.5)
image(USCounties[1:200,1:200], lwd=.01)