Marcelino & All--
If, by random, you mean either equal inclusion probability (of points or
transects) or even known/computable inclusion probability (e.g., for
Horvitz-Thompson estimators of properties of the entire polygon), be wary of
edges and think very carefully about what exactly you are gen
2009/2/12 Marcelino de la Cruz :
>
> As an spatstat aficionado, I would use the following code:
Very very nice, but:
> #compute a circle around each point
> cosadisc<- apply(cosaxy,1, function(x) disc(r=ltransect, x))
generates 128 points on a circle around each point. There's a teeny
tiny cha
As an spatstat aficionado, I would use the following code:
Enjoy!
Marcelino
library(spatstat)
# Define polygon, length of transect and number of (points)transects
data(letterR)
mywindow <- letterR
ltransect <- 0.3
npoints <- 100
s<- 1:npoints
# Generate random origin points
cosa <- runifpoi
2009/2/12 Pierre Racine :
> Hi,
>
> Anybody knows a tool or algorythm (R, GRASS or ArcGIS Script, anything!)
> to generate a number of random same length transects (e.g. 1000) within
> the extent of a given polygon or raster?
>
> I can't just create random point in the extent and joint hem two by t
On Thu, 12 Feb 2009, Don MacQueen wrote:
I feel a bit lazy asking for help, as I know I can do this -- but since I
don't work with spatial polygons frequently, I find assembling objects
consisting of nested polygons to be a bit challenging.
It can be done, so this approach from the other side
Hi,
Anybody knows a tool or algorythm (R, GRASS or ArcGIS Script, anything!)
to generate a number of random same length transects (e.g. 1000) within
the extent of a given polygon or raster?
I can't just create random point in the extent and joint hem two by two.
This would result in different len
Well to move an island you are going to need a really big ship with a really
big crane ...
Ok, on a more serious note. Here is one approach that may work for you (a
different idea from what you suggest below):
library(maptools)
library(TeachingDemos)
dnk <- readShapePoly('g:/downloads/DNK_adm
Hi all,
I'm trying to compute adaptive kernel density estimation in R (multivariate
data), using the k-nearest neighbour method for selecting the bandwidth.
I found locfit (only for univariate) and I tried the Kernsur in GenKern
package (which says it can use non equally spaced and adaptive bandw
I feel a bit lazy asking for help, as I know I can do this -- but
since I don't work with spatial polygons frequently, I find
assembling objects consisting of nested polygons to be a bit
challenging.
I have a Spatial Polygons Data Frame object named "s2poly" (read in
from a polygons shapefile
On Thu, 12 Feb 2009, Peter Jepsen wrote:
Dear all,
I have only just begun plotting on maps, so please bear with me. I am
plotting a map of Denmark in which each county is colorcoded by its
incidence of a particular disease. I am using the map data found at
http://biogeo.berkeley.edu/bgm/gdatare
On Thu, 12 Feb 2009, Ned Horning wrote:
Roger,
Thanks - It looks like this will do the trick. I had to change
[X$covertype="forest",] to [X$covertype=="forest",] but it appears to work
just fine.
Yes, of course, my mistake. Nice to know it worked after correction.
Roger
Ned
Roger Bivan
Roger,
Thanks - It looks like this will do the trick. I had to change
[X$covertype="forest",] to [X$covertype=="forest",] but it appears to
work just fine.
Ned
Roger Bivand wrote:
On Thu, 12 Feb 2009, Ned Horning wrote:
Roger and Robert,
Thanks for the help. Once again I am close but I c
On Thu, 12 Feb 2009, Ned Horning wrote:
Roger and Robert,
Thanks for the help. Once again I am close but I can't figure out how to use
the attribute data to control the sampling. I'd like to stratify the sampling
by attribute value. In the Shapefile I have an integer attribute "covertype".
T
Roger and Robert,
Thanks for the help. Once again I am close but I can't figure out how to
use the attribute data to control the sampling. I'd like to stratify the
sampling by attribute value. In the Shapefile I have an integer
attribute "covertype". There can be several polygons with the same
Dear all,
I have only just begun plotting on maps, so please bear with me. I am
plotting a map of Denmark in which each county is colorcoded by its
incidence of a particular disease. I am using the map data found at
http://biogeo.berkeley.edu/bgm/gdatares.php. The map is perfect, but the
island of
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