[R-sig-Geo] quadracount on multitype points

Guy Bayegnak Guy.Bayegnak at gov.ab.ca
Wed Sep 13 01:08:37 CEST 2017

Thanks a lot for your response and suggestion Rolf.  Yes, by "quadrant" I mean the little sub-windows.  My problem is the following:

We have collected thousands of groundwater samples across a vast area, and analysed them. Based on the analysis we are able to assign a "type" to each water sample.  When plotted, there seems to be a spatial trend in water type. But a given area may have more than one water type,  usually with a dominant type (most frequently occurring). What I am trying to do is identify the dominant type for each sub-region /sub-windows but show the count side by side, for example:

 y         [0,0.801)            [0.801,1.6]
  [0.5,1]   Off =     36                Off =  6
           On =   3     On = 39

   [0,0.5)   Off =  4              Off = 36
            On = 42        On = 6

I think I can achieve what I am looking for with your suggestion. Once I get the table list, I will copy the numbers side by side manually.



-----Original Message-----
From: Rolf Turner [mailto:r.turner at auckland.ac.nz]
Sent: September 12, 2017 3:45 PM
To: Guy Bayegnak <Guy.Bayegnak at gov.ab.ca>
Cc: r-sig-geo at r-project.org; Adrian.Baddeley at curtin.edu.au; Ege Rubak <rubak at math.aau.dk>
Subject: Re: [R-sig-Geo] quadracount on multitype points

On 13/09/17 02:11, Guy Bayegnak wrote:

> Dear all,
> I am working on a multitype point pattern, and I'd like to estimate
> how many of each type of point occurs into each quadrant. I know it is
> possible to use the quandracount on split marks as follows using
> spatstats: quadratcount(split(marks)). But the result produces as many
> windows as they are marks. I am wondering is there is a way to know
> many occurrence of each type there is per quadrant and to plot it in a
> single grid.
> Thanks.

You really should start by mentioning that you are dealing with the spatstat package.

It's not clear to me what you are after.  A minimal reproducible example would be helpful.  I presume that by "quadrant" you mean one of the four equal sub-windows formed by bisecting your (rectangular) window vertically and horizontally.

If my presumption is correct then perhaps


(where "X" is your point pattern) does what you want.  E.g.:

> lapply(split(amacrine),quadratcount,nx=2)
> $off
>          x
> y         [0,0.801) [0.801,1.6]
>   [0.5,1]        36          36
>   [0,0.5)        34          36
> $on
>          x
> y         [0,0.801) [0.801,1.6]
>   [0.5,1]        35          39
>   [0,0.5)        42          36

Is this something like what you wish to achieve?


Rolf Turner

Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276
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