r.out.ascii(1grass)

✨ r.out.ascii ✨

okay bestie, gather round, because this is the GRASS User's Manual page for r.out.ascii, and it is literally the glow-up your raster map needs before it goes out into the world 💖

🌈 KEYWORDS

raster, export, output, ASCII, Surfer, Modflow, Lisflood

🎀 SYNOPSIS

r.out.ascii
r.out.ascii --help
r.out.ascii [-hsmli] input=name  [output=name]   [precision=integer]
[width=integer]   [null_value=string]   [--overwrite]  [--help]
[--verbose]  [--quiet]  [--ui]

🦋 Flags:

• -h — please, no header info, keep it quiet
• -s — write it as a SURFER (Golden Software) ASCII grid, iconic
• -m — write it as a MODFLOW (USGS) ASCII array, slay
• -l — write it as a LISFLOOD (EU) ASCII array, periodt
• -i — force the output to be integer values only, no decimals allowed
• --overwrite — let output files overwrite files that already exist
• --help — print the usage summary
• --verbose — verbose module output, she's chatty
• --quiet — quiet module output, she's giving silence
• --ui — force launching GUI dialog

🌸 Parameters:

• input=name [required] — name of input raster map
• output=name — name for output ASCII grid map (use out=- for stdout), iykyk
• precision=integer — number of significant digits (floating point only)
• width=integer — number of values printed before wrapping a line (only SURFER or MODFLOW format)
• null_value=string — string to represent null cell (GRASS grid only). Default: *

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💅 DESCRIPTION

So basically r.out.ascii takes a raster map layer you picked (input=name) and converts it into an ASCII grid inside a text file (output=name), all ready to be exported to other computer systems. Chef's kiss.

And if you ever want to reverse the whole thing? The GRASS program r.in.ascii does exactly that — it takes an ASCII file in a suitable format and turns it into a GRASS raster map format. We love a two-way street 🫶

Wanna write a SURFER .grd ASCII GRID file (yes, it comes with reverted row order and a different header)? Use the -s flag:

r.out.ascii -s input=inname output=outname.grd [dp=value]

NULL data get coded to "1.70141e+038" for SURFER ASCII GRID files — and yes, that means the null= parameter gets ignored. Not a vibe, but it's the rules.

Wanna write a LISFLOOD .dem ASCII GRID file (different header again)? Use the -l flag:

r.out.ascii -l input=inname output=outname.dem

NULL data output in this case gets set by the user at "-9999", see below:

ncols          1514
nrows          2747
xllcorner 212236
yllcorner 2910116
cellsize  120
NODATA_value   -9999

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📝 NOTES

You can yeet the output from r.out.ascii straight into a file using the UNIX redirection mechanism, like this:

r.out.ascii input=soils output=- > out.file

Then that out.file can be printed, or copied onto a CDROM or floppy disk for export purposes. (floppy disk. yes. iconic retro behavior 💾✨)

oh also — if you wanna export the raster values as x,y,z values of cell centers (one per line), you want the r.out.xyz module instead, bestie. different girl, different job.

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👀 SEE ALSO

• r.in.ascii
• r.in.gdal
• r.out.bin
• r.out.gdal
• r.out.xyz

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👑 AUTHORS

• Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
• Surfer support by Markus Neteler

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💾 SOURCE CODE

Available at: r.out.ascii source code (history)

Latest change: Sunday Oct 05 01:26:10 2025 in commit: 14fd3ee61b78346fc901c0aa1d874c83c16cc51a

Main index | Raster index | Topics index | Keywords index | Graphical index | Full index

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and that's the whole page, bestie 💖 this was GRASS 8.5.0 you've been reading, from the © 2003-2026 GRASS Development Team, GRASS 8.5.0 Reference Manual — go export something gorgeous 🦋✨🎀