[R] looping through spatial points and getting counts of spatial points in spatial grid in R

Tilottama Ghosh waggymaggy at yahoo.com
Mon Dec 17 10:24:03 CET 2012


Hi,
Following Anthony's reply I am attaching two of the POI shapefiles and the code for creating the spatial grid. I am not being able to read the list of these shapefiles and then perform the points in spatial grid function. If someone can help, I will be very grateful.
Here is my code for creating the spatial grid -Gridtopo_LS = GridTopology(cellcentre.offset = c(68.162500,6.754167), cellsize = c(0.008333333,0.008333333), cells.dim = c(3508,3451))class (Gridtopo_LS)SpatialGrid_LS = SpatialGrid (Gridtopo_LS, proj4string = CRS("+proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0"))bbox (SpatialGrid_LS)class(SpatialGrid_LS)summary (SpatialGrid_LS)plot (SpatialGrid_LS,pch=3)

Thanks very much,
Tilo


--- On Mon, 17/12/12, Tilottama Ghosh <waggymaggy at yahoo.com> wrote:

From: Tilottama Ghosh <waggymaggy at yahoo.com>
Subject: looping through spatial points and getting counts of spatial points in spatial grid in R
To: r-help at r-project.org
Date: Monday, 17 December, 2012, 0:07

Hi,
I am stuck in a looping problem. It might be an easy problem for experienced R users but I have been unable to do it. Any kind of help or advice will be great appreciated.
I am creating a spatial grid and have a list of spatial points in a folder. I can read the spatial points separately and get a count of the points in the spatial grid in R. The output should be a table showing the counts of points in the spatial grid. However, since there are many of these spatial points, I want this process to be automated. Can someone help me with this? All my spatial points are in one folder. 
# Creating spatial points in R - reading the POI shapefiles as SpatialPointsDataFrame in R autopts.rg <- readOGR(".", "AutoSvc")class
 (autopts.rg)

# Getting a count of the Spatial Points in the Spatial Data Frame in.cell <- overlay(SpatialGrid_LS,FinInstq2) newdata <- data.frame(table(in.cell))View(newdata)
"SpatialGrid_LS" is the spatial grid that I had created in R. 
I guess a For loop would help, but although I tried several things, I haven't been successful yet.
Thanks!
Tilo



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