R: Ascii Grid Files to Dataframe and Dataframe to Ascii Grid...

asc2dataframe {SDMTools} | R Documentation

## 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

### 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.

### 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.

### Author(s)

Lorena Falconi lorefalconi@gmail.com

### 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')

[Package SDMTools version 1.1-221.2 Index]