image | R Documentation |
The function creates a grid of colored rectangles with
colors corresponding to the values of the spam
matrix.
## S4 method for signature 'spam'
image(x, cex = NULL, ...)
x |
matrix of class |
cex |
for very large matrices, the dot size may need to be scaled. |
... |
any other arguments passed
to |
getOption("spam.imagesize")
determines if the sparse matrix is
coerced into a matrix and the plotted similarly to image.default
or if
the matrix is simply represented as a scatterplot with
pch="."
. The points are scaled according to
cex*getOption("spam.cex")/(nrow+ncol)
.
For some devices or for non-square matrices,
cex
needs probably some adjustment.
The a zero matrix in spam
format has as (1,1) entry the value
zero and only missing entries are interpreted as NA
in the
scatter plot.
Reinhard Furrer
display
and spam.options
.
The code is based on image
of graphics
.
set.seed(13)
smat <- spam_random(8)
par(mfcol=c(1,2),pty='s')
options(spam.imagesize=1000)
image(smat) # or use better color schemes
options(spam.imagesize=10)
image(smat, cex=.25)
smat <- spam_random(2^14, distribution=rnorm, density=1e-5, verbose=TRUE)
par(mfcol=c(1,1), mai=c(.4,.4,.1,.1), pty='s')
image(smat)
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