On Mon, Jan 15, 2018 at 8:41 PM, Veronica Andreo <veroandreo@gmail.com> wrote:
Hi all,
2018-01-15 20:11 GMT+01:00 Markus Neteler <neteler@osgeo.org>:
On Mon, Jan 15, 2018 at 5:27 PM, Paulo van Breugel
<p.vanbreugel@gmail.com> wrote:
On 1/15/18 4:39 PM, Markus Metz wrote:
…
the manual is wrong:
Use the file option to analyze large amount of raster maps without hitting
open files limit and the size limit of command line arguments.
must be
Use the -z flag to analyze large amount of raster maps without hitting open
files limit and the file option to avoid hitting the size limit of command
line arguments.
Ah, yes, I totally forgot about that flag. Thanks (also Anna and Veronica).
Perhaps somebody with write permission can correct his in the manual page?
Done in r72081: please verify. I think it could still be better.
https://trac.osgeo.org/grass/changeset/72081
AFAIU, the file option does not necessarily make the process slower (it just replaces a list of comma separated maps in a command by a file), it is the -z flag that does that, because it will open and close files once and again, instead of keeping them open (Am I right, @markusM?)
Moreover, I checked r.hants and r.series.lwr, which are based on r.series and have the same file option and -z flag. They all have different wording. Maybe we could agree here on the 3 of them. From my understanding, they are not entirely correct. Here the text snippets:
r.hants:
“Use the file option to analyze large amount of raster maps without hitting open files limit and the size limit of command line arguments. The computation is slower than with the input option method. For every single row in the output map(s) all input maps are opened and closed. The amount of RAM will rise linearly with the number of specified input maps. The input and file options are mutually exclusive. The option input is a comma separated list of raster map names and the option file is a text file with a new line separated list of raster map names. Note that the order of maps in one option or the other is very important.”
r.series.lwr:
“Use the -z flag to analyze large amounts of raster maps without hitting the open files limit and the size limit of command line arguments. This will however increase the processing time. For every single row in the output map(s) all input maps are opened and closed. The amount of RAM used will rise linearly with the number of specified input maps.The input and file options are mutually exclusive. Input is a text file with a new line separated list of raster map names”
I can change them accordingly once we understand correctly the effect of both file option and -z flag.
The manual of r.series is IMHO now correct. The file option avoids hitting the size limit of command line arguments, and the -z flag avoids hitting the limit of the number of open files.
In all three manuals, the sections starting with “The maximum number of raster maps” (in r.series “Number of raster maps to be processed”) should be identical. Ideally, the manual of r.hants or r.series.lwr would be used as template, adding the latest change of r.series with regard to the file option and the -z flag, then sync all manuals.
Which other modules share this -z flag?
r.series.accumulate
t.rast.series and t.rast.aggregate do not have the -z flag, but should probably have it because they call r.series.
Markus M
best,
Vero
