Write matrix to an ASCII raster file

Description

Writes a data frame to an ASCII raster file, suitable for display in a Geographic Information System.

Usage

1
epi.asc(dat, file, xllcorner, yllcorner, cellsize, na = -9999)

Arguments

dat

a matrix with data suitable for plotting using the image function.

file

character string specifying the name and path of the ASCII raster output file.

xllcorner

the easting coordinate corresponding to the lower left hand corner of the matrix.

yllcorner

the northing coordinate corresponding to the lower left hand corner of the matrix.

cellsize

number, defining the size of each matrix cell.

na

scalar, defines null values in the matrix. NAs are converted to this value.

Value

Writes an ASCII raster file (typically with *.asc extension), suitable for display in a Geographic Information System.

Note

The image function in R rotates tabular data counter clockwise by 90 degrees for display. A matrix of the form:

1 3
2 4

is displayed (using image) as:

3 4
1 2

It is recommended that the source data for this function is a matrix. Replacement of NAs in a data frame extends processing time for this function.

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