Message-ID: <AANLkTi=4xedv6vN8zzryeH=seKiSs9gSMefFk+WmDE0M@mail.gmail.com>
Date: 2010-10-19T11:54:19Z
From: Barry Rowlingson
Subject: Creating density heatmaps for geographical data
In-Reply-To: <i9jtkb$chr$1@dough.gmane.org>
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