the details section of ?image says:
If useRaster is not specified, raster images are used when the
getOption("preferRaster") is true, the grid is regular and either
dev.capabilities("raster") is "yes" or it is "non-missing" and there
are no missing values.
but in my experience this is never the case and
getOption("preferRaster") is ignored. As far as I can see, the logic for
checking this is in image is broken here:
ras <- dev.capabilities("raster")
if (identical(ras, "yes"))
useRaster <- TRUE
because dev.capabilities("raster") returns a list like this (on my
machine, R.version in footer)
$rasterImage
[1] "yes"
You can test this by doing:
ras=structure(list(rasterImage = "yes"), .Names = "rasterImage")
identical(ras,'yes') # returns FALSE
so the test would need to be something like:
ras <- dev.capabilities("raster")[[1]]
if (identical(ras, "yes"))
useRaster <- TRUE
I can't find any relevant changes in R news
http://stat.ethz.ch/R-manual/R-devel/doc/html/NEWS.html
This discussion
https://www.mail-archive.com/r-devel@r-project.org/msg22811.html
suggests that Simon Urbanek may have added the useRaster option and
looking at git blame on this mirror repo:
https://github.com/wch/r-source/blame/c3ba5b0be36d3a1290e18fe189142c88f1e43236/src/library/graphics/R/image.R#L111-L120
suggests that Brian Ripley's svn commit 56949 was the last to touch
these lines:
https://github.com/wch/r-source/commit/b9012424f895bf681daf1b85255942547d495bcd
Thanks for any pointers if I am missing something!
Best wishes,
Greg Jefferis.
R.version
_
platform x86_64-apple-darwin10.8.0
arch x86_64
os darwin10.8.0
system x86_64, darwin10.8.0
status
major 3
minor 0.3
year 2014
month 03
day 06
svn rev 65126
language R
version.string R version 3.0.3 (2014-03-06)
nickname Warm Puppy
--
Gregory Jefferis, PhD
Division of Neurobiology
MRC Laboratory of Molecular Biology
Francis Crick Avenue
Cambridge Biomedical Campus
Cambridge, CB2 OQH, UK
http://www2.mrc-lmb.cam.ac.uk/group-leaders/h-to-m/g-jefferis
http://jefferislab.org
http://flybrain.stanford.edu
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