[GRASS-dev] odd behavior from t.register when loading from file and no "end date" is specified

[Dylan Beaudette]

On Wed, Oct 14, 2015 at 5:10 AM, Veronica Andreo <veroandreo at gmail.com> wrote:
> Hi Dylan,
>
> I guess -i flag "might" (not sure) be incompatible with a file with
> start_time... so, if you have a list with mapname|start_time, you would only
> pass that and no need to set an increment really, because it would be
> implicit in the start_time (of course if your maps have different
> granularities, then you need to specify start and end time)... this is what
> I get with your example:
>
> GRASS 7.1.svn (latlong_wgs84):~ > t.register --o input=precip_abs
> file=precip_abs.files type=raster
> ...
>
> GRASS 7.1.svn (latlong_wgs84):~ > t.rast.list precip_abs
> name|mapset|start_time|end_time
> prec_1|pruebas|1981-01-01 00:00:00|None
> prec_2|pruebas|1981-01-02 00:00:00|None
> prec_3|pruebas|1981-01-03 00:00:00|None
> prec_4|pruebas|1981-01-04 00:00:00|None
> prec_5|pruebas|1981-01-05 00:00:00|None
> prec_6|pruebas|1981-01-06 00:00:00|None

Hi Veronica,

I have often wondered if some of the arguments to t.register were
mutually exclusive. Perhaps this is a documentation opportunity. Happy
to help with that.

The output you list above matches my observations. I can still do most
of my work with no end_time defined--the resulting STRDS is "point"
support--however, t.mapcalc complains when using multiple "point"
support STRDS as input. Thus, I have been trying to register my daily
data as "interval" support.


> If I use the list of mapnames only (without start_time) and so, I set -i
> flag, increment="1 days" and start="1981-01-01", then I get:
>
> GRASS 7.1.svn (latlong_wgs84):~ > t.register --o -i input=precip_abs
> file=somefile type=raster increment="1 days" start="1981-01-01"
> ...
> GRASS 7.1.svn (latlong_wgs84):~ > t.rast.list precip_abs
> name|mapset|start_time|end_time
> prec_1|pruebas|1981-01-01 00:00:00|1981-01-02 00:00:00
> prec_2|pruebas|1981-01-02 00:00:00|1981-01-03 00:00:00
> prec_3|pruebas|1981-01-03 00:00:00|1981-01-04 00:00:00
> prec_4|pruebas|1981-01-04 00:00:00|1981-01-05 00:00:00
> prec_5|pruebas|1981-01-05 00:00:00|1981-01-06 00:00:00
> prec_6|pruebas|1981-01-06 00:00:00|1981-01-07 00:00:00


Interesting! This is my "expected" output, and indeed I can replicate
this behavior on my machine. I am using r66489.

Can you reproduce the behavior as described in my original posting,
when using a file specifying the start date _and_ and arguments: "-i
increment='1 days'" ?

Thanks!
Dylan


> I'm using r66429
>
> HTH,
> Vero
>
> 2015-10-13 18:10 GMT-03:00 Dylan Beaudette <dylan.beaudette at gmail.com>:
>>
>> Hi,
>>
>> I recently notices something when working with t.register and a large
>> collection of daily files. My typical work-flow is something like
>> this:
>>
>> # make some data
>> r.mapcalc expression="prec_1 = 100"
>> r.mapcalc expression="prec_2 = 200"
>> r.mapcalc expression="prec_3 = 300"
>> r.mapcalc expression="prec_4 = 400"
>> r.mapcalc expression="prec_5 = 500"
>> r.mapcalc expression="prec_6 = 600"
>>
>> # create a new space-time data set
>> t.create --o type=strds temporaltype=absolute \
>>     output=precip_abs title="Example" \
>>     descr="Example"
>>
>> # generate a file describing the raster names and start dates
>> echo "prec_1|1981-01-01|
>> prec_2|1981-01-02|
>> prec_3|1981-01-03|
>> prec_4|1981-01-04|
>> prec_5|1981-01-05|
>> prec_6|1981-01-06|" > precip_abs.files
>>
>>
>> ... In many cases the list of raster and dates is generated by parsing
>> raster names, like this:
>>
>> g.list type=rast pattern="file_*" | \
>> awk -F '_' '{print
>> $1"_"$2"|"substr($2,1,4)"-"substr($2,5,2)"-"substr($2,7,2)}' >
>> somefile
>>
>> ... this is really handy when you have a lot of files (>10k), but
>> cannot generate both "start" and "stop" dates for the t.register input
>> file.
>>
>> OK, well (unless I am mistaken) t.register should be able to figure
>> this out when invoked with the "-i" flag:
>>
>> # register maps from file, filling-in stop dates
>> t.register --o -i input=precip_abs file=precip_abs.files type=raster
>> increment="1 day"
>>
>> ... however, this results in the following:
>>
>> # double-check start | stop dates:
>> t.rast.list precip_abs
>>
>> name|mapset|start_time|end_time
>> prec_1|PERMANENT|1981-01-02 00:00:00|1981-01-03 00:00:00
>> prec_2|PERMANENT|1981-01-03 00:00:00|1981-01-04 00:00:00
>> prec_3|PERMANENT|1981-01-04 00:00:00|1981-01-05 00:00:00
>> prec_4|PERMANENT|1981-01-05 00:00:00|1981-01-06 00:00:00
>> prec_5|PERMANENT|1981-01-06 00:00:00|1981-01-07 00:00:00
>> prec_6|PERMANENT|1981-01-07 00:00:00|1981-01-08 00:00:00
>>
>> ... these maps are offset by 1 day into the future.
>>
>> Is this the intended result?
>>
>> I am able to get my expected result if I fully specify the start and
>> stop dates in the t.register input file. This get a little tricky, but
>> (insert your favorite scripting language) can make the process of
>> adding 1 day to each line simple.
>>
>>
>> This is with grass_trunk as of:
>>
>> Last Changed Rev: 66487
>> Last Changed Date: 2015-10-13 02:54:55 -0700 (Tue, 13 Oct 2015)
>>
>>
>> Am I abusing t.register or otherwise misinterpreting the manual pages?
>>
>> Thanks,
>> Dylan
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>
>