R help - Oct 2008 - Spatstat - Several density plots using the same scale

Hi everyone,

I am using the package "spatstat" for ploting kernel maps of my data.
It is a marked point pattern, the result of mosquito surveillance in a
area in a week.
For each trap, the number of individuals captured is the mark of the point.
> plot(density(X, weights=X$marks))
makes a nice kernel, but the problem is that I've got several weeks and
for each week the density is re-scaled, which makes comparisons useless.
I've been trying to find some way to pass the scale limits to the function
but just couldn't find.

Hope someone can help
Thanks
Arthur

On 10/10/2008, at 4:48 AM, Arthur Weiss wrote:
> Hi everyone,
>
> I am using the package "spatstat" for ploting kernel maps of my
data.
> It is a marked point pattern, the result of mosquito surveillance in a
> area in a week.
> For each trap, the number of individuals captured is the mark of  
> the point.
>
>> plot(density(X, weights=X$marks))
>
> makes a nice kernel, but the problem is that I've got several weeks  
> and
> for each week the density is re-scaled, which makes comparisons  
> useless.
> I've been trying to find some way to pass the scale limits to the  
> function
> but just couldn't find.
Not quite sure what the problem is ... but the help for plot.im() says:

				.
				.
				.

           numeric-valued images: By default, the range of pixel  
values in
           'x' is divided into 'n = length(col)' equal
subintervals,
           which are mapped to the colours in 'col'. (If 'col'
was not
           specified, it defaults to a vector of 255 colours.)

           Alternatively if the argument 'zlim' is given, it should be a
           vector of length 2 specifying an interval of real numbers.
           This interval will be used instead of the range of pixel
           values. The interval from 'zlim[1]' to 'zlim[2]' will
be
           mapped to the colours in 'col'. This facility enables the
           user to plot several images using a consistent colour map.

Does setting the zlim argument accomplish what you want?  If not, please
get back to us with more detail.

	cheers,

		Rolf Turner

######################################################################
Attention:\ This e-mail message is privileged and confid...{{dropped:9}}