SDMTools (version 1.1-221)

asc2dataframe: Ascii Grid Files to Dataframe and Dataframe to Ascii Grid Files

Description

asc2dataframe converts a list of Esri ascii grid formatted files to a data.frame consisting of only locations with data. dataframe2asc converts a data.frame or matrix with spatial data to Esri ascii grid formatted files.

Usage

asc2dataframe(filenames, varnames = NULL, gz = FALSE)
dataframe2asc(tdata, filenames = NULL, outdir = getwd(), gz = FALSE)

Arguments

filenames

is a vector of file names

varnames

is a vector of names for the output columns, and must be the same length as files

tdata

is the data.frame which has y, x coordinates (OR lat,lon) and columns for the data to be output (MUST be in that order)

outdir

is the output directory, the default is the current working directory

gz

boolean defining if the ascii grid files are gzip compressed

Value

asc2dataframe

Returns a dataframe with XY coordinates and the data of each ascii grid files, as columns.

dataframe2asc

Returns an asc grid file for each data column within the data.frame.

Details

asc2dataframe: The ascii grid files can be read in gzip compress format. The dataframe returned contains the X and Y coordinate columns followed by columns of data.

dataframe2asc: If filenames is null, column names will be used. The data.frame has to contain the Y and X coordinates and the data as columns. The ascii grid files can be created as gzip compress format and would be saved in the outdir.

Examples

#Create 2 ascii files
y=seq(10,50,0.5)
x=seq(140,180,0.5)
cellsize=0.5
data1=sample(160,140)
data2=sample(158,140)
out1.asc=as.asc(matrix(data1,nc=y, nr=x), xll=min(x), yll=min(y), cellsize=cellsize)
out2.asc=as.asc(matrix(data2,nc=y, nr=x), xll=min(x), yll=min(y), cellsize=cellsize)
#write the ascii files to the work directory
write.asc(out1.asc, 'out1.asc')
write.asc(out2.asc, 'out2.asc')
#list the ascii files
ascfiles=c('out1.asc', 'out2.asc')
#generate a dataframe from the ascii files
tdata=asc2dataframe(ascfiles)
tdata

#remove the files
unlink('out1.asc'); unlink('out2.asc')

#convert the dataframe tdata to ascii grid files
dataframe2asc(tdata)

#remove the files
unlink('var.1.asc'); unlink('var.2.asc')