[R-sig-Geo] Creating density heatmaps for geographical data

[Barry Rowlingson]

On Tue, Oct 19, 2010 at 11:58 AM, Karl Ove Hufthammer <karl at huftis.org> wrote:

> And though the ‘window’ element of ‘ppp’ objects may be of use to some
> people, I haven’t had any use for it. The annoying thing here is that the
> constructor doesn’t generate the window automatically, based on the extent /
> bounding box of the data, and don’t have an *option* for doing this, either.
> Whenever I have used ‘spatstat’ (not too often), I have had to spend too
> much time looking up how the window should be specified. Having [0,1] ×
> [0,1] as the *default* window, and excluding any points outside this does
> seems like a strange design decision.

 I had this 'argument' with Rolf and Adrian a few years ago during a
very nice stay in Perth with them. spatstat is not about (geo)spatial
data - it's about statistical point pattern analysis. A statistical
point pattern is only well-defined when there's a window. Otherwise it
aint a point pattern. And spatstat doesn't have any business with
non-spatial point patterns! :)

 There's a lot of functionality in spatstat that people want to use in
other contexts, such as some of the transformations or window
manipulation functions, and I think these could be usefully taken out
and put into a package that works with sp-class objects.

 But ppp objects are perfectly understandable and sensible if all you
do is point pattern analysis!

Barry