R help - Jan 2013 - lapply and SpatialGridDataFrame error

Hi all, I have a set of 54 files that I need to convert from ASCII grid
format to .shp files to .bnd files for BayesX.

I have the following R code to operate on those files:

library(maptools)
library(Grid2Polygons)
library(BayesX)
library(BayesXsrc)
library(R2BayesX)

readfunct <- function(x)
{
u <- readAsciiGrid(x)
}

modfilesmore <- paste0("MaxFloodDepth_", 1:54, ".txt")
modeldepthsmore <- lapply(modfilesmore, readfunct)

maxdepth.plys <- lapply(modeldepthsmore, Grid2Polygons(modeldepthsmore,
level = FALSE))

layers <- paste0("examples/floodlayers_", 1:54)
polyshapes <- lapply(writePolyShape(maxdepth.plys, layers))
shpName <- sub(pattern="(.*)\\.dbf", replacement="\\1",
x=system.file("examples/Flood/layer_.dbf",
package="BayesX"))
floodmaps <- lapply(shp2bnd(shpname=shpName, regionnames="SP_ID"))

## draw the map
drawmap(map=floodmaps)


This is the error message that I receive:
> maxdepth.plys <- lapply(modeldepthsmore,
Grid2Polygons(modeldepthsmore, level = FALSE))
Error in Grid2Polygons(modeldepthsmore, level = FALSE) : Grid object not
of class SpatialGridDataFrame


Can someone assist me in modifying the R code so that I can convert the
set of files to .shp files and then to .bnd files for BayesX?

Thank-you.

Irucka Embry 


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Irucka Embry <iruckaE <at> mail2world.com> writes:
> 
> Hi all, I have a set of 54 files that I need to convert from ASCII grid
> format to .shp files to .bnd files for BayesX.
> 
> I have the following R code to operate on those files:
> 
> library(maptools)
> library(Grid2Polygons)
> library(BayesX)
> library(BayesXsrc)
> library(R2BayesX)
> 
> readfunct <- function(x)
> {
> u <- readAsciiGrid(x)
> }
> 
> modfilesmore <- paste0("MaxFloodDepth_", 1:54,
".txt")
> modeldepthsmore <- lapply(modfilesmore, readfunct)
> 
> maxdepth.plys <- lapply(modeldepthsmore, Grid2Polygons(modeldepthsmore,
> level = FALSE))
> 
...
> 
> This is the error message that I receive:
> > maxdepth.plys <- lapply(modeldepthsmore,
> Grid2Polygons(modeldepthsmore, level = FALSE))
> Error in Grid2Polygons(modeldepthsmore, level = FALSE) : Grid object not
> of class SpatialGridDataFrame
> 
> Can someone assist me in modifying the R code so that I can convert the
> set of files to .shp files and then to .bnd files for BayesX?
You also posted on R-sig-geo a few hours after posting here - certainly a more
relevant choice of list, but you are rather impatient.

I'm assuming that you have read up on how lapply() works, and realised what
is
wrong with your understanding. But just in case, 
> maxdepth.plys <- lapply(modeldepthsmore, Grid2Polygons(modeldepthsmore,
> level = FALSE))
does not pass the list component from modeldepthsmore anywhere, but tries to run
Grid2Polygons on the whole list. Something like (untried):

maxdepth.plys <- lapply(modeldepthsmore, function(x) Grid2Polygons(x, level
FALSE))

should do that. Please summarise to R-sig-geo.

Roger

> 
> Thank-you.
> 
> Irucka Embry 
>