[Rd] support for POSIXct classes in image.default axes
Prof Brian Ripley
ripley at stats.ox.ac.uk
Wed Apr 17 10:15:57 CEST 2013
On 12/04/2013 12:27, Michael Sumner wrote:
> Hello, I would like to suggest the following change to image.default in
> < plot(NA, NA, xlim = xlim, ylim = ylim, type = "n", xaxs = xaxs,
>> plot(x, y, xlim = xlim, ylim = ylim, type = "n", xaxs = xaxs,
I think xlim, ylim is a better idea: this relies on range() preserving
Done now (in R-devel pro tem).
> This provides all the support of axis.POSIXt that plot.default gives,
> currently the default new plot in image.default uses NAs and the axis class
> is ignored. This is nice for plotting time series data stored in a matrix.
> Here's a dummy example that shows usage with my change:
> x <- list(x = Sys.time() + seq(1, 1e6, length = nrow(volcano)), y =
> 1:ncol(volcano), z = volcano)
> ## date-time formatting on the x-axis
> ## date-time formatting on the y-axis
> image(x$y, x$x, t(x$z))
> Without the change we get the very large underlying numeric values for the
> times on the axis.
> We can still override the default axis to do a workaround: :
> image(x, axes = FALSE)
> axis.POSIXct(x$x, side = 1)
> Cheers, Mike.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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