[GRASS-dev] Temporal framework: Proper way to register new maps from a python module?

[Sören Gebbert]

Hi Laurent,
please do not use the legacy r.timestamp module to set the time stamp
for maps. The feature to use time stamps set by r.timestamp was only
implemented, to migrate from old grass locations with time stamped
maps to the temporal framework approach more easily. I am not sure if
this works well with relative time.

The easiest way is to generate a text file with name, start time and
end time. If you insist to avoid using text files, then generate a
list of RasterDataset[1] objects, set the time for these objects
(set_absolute_time() or set_relative_time()) and use
register_map_object_list() [2] to register them in a space time raster
dataset.

[1] https://grass.osgeo.org/grass70/manuals/libpython/temporal.html#temporal.space_time_datasets.RasterDataset
[2] https://grass.osgeo.org/grass70/manuals/libpython/temporal.html#temporal.register.register_map_object_list

Best regards
Soeren

2015-10-09 17:13 GMT+02:00 Laurent C. <lrntct at gmail.com>:
> Hello,
>
> I'm writing a module that generates raster maps and register them in
> newly created strds.
> The temporal type of the generated strds depends on the entry values
> of the module.
> I've seen in the documentation that
> register_maps_in_space_time_dataset() can read the timestamp from the
> GRASS raster, so my module is currently doing the following:
>  - writes maps
>  - assign timestamp, either absolute or relative with r.timestamp
>  - at the end, register all the generated maps from a list using
> register_maps_in_space_time_dataset()
>
> But I end up with the following error with relative time:
> File "/home/lo/Programación/t_sim_flood/gis.py", line 286, in
> register_maps_in_strds
>     strds_id, maps=map_lst_str, unit='seconds')
>   File "/usr/lib/grass71/etc/python/grass/temporal/register.py", line
> 289, in register_maps_in_space_time_dataset
>     statement += map.insert(dbif=dbif, execute=False)
>   File "/usr/lib/grass71/etc/python/grass/temporal/abstract_map_dataset.py",
> line 273, in insert
>     self.write_timestamp_to_grass()
>   File "/usr/lib/grass71/etc/python/grass/temporal/space_time_datasets.py",
> line 242, in write_timestamp_to_grass
>     self._convert_timestamp())
>   File "/usr/lib/grass71/etc/python/grass/temporal/abstract_map_dataset.py",
> line 124, in _convert_timestamp
>     start = datetime_to_grass_datetime_string(start_time)
>   File "/usr/lib/grass71/etc/python/grass/temporal/datetime_math.py",
> line 817, in datetime_to_grass_datetime_string
>     if dt.tzinfo is not None:
> AttributeError: 'NoneType' object has no attribute 'tzinfo'
>
> The grass timestamp are well written and are visible with r.info.
> If I give a start=0 to register_maps_in_space_time_dataset(), all the
> maps are registered in the strds without generating errors, but they
> all starts and ends at 0:
>  +-------------------- Relative time -----------------------------------------+
>  | Start time:................. 0
>  | End time:................... 0
>  | Relative time unit:......... seconds
>  | Granularity:................ 0
>  | Temporal type of maps:...... point
>  +-------------------- Spatial extent ----------------------------------------+
>
> And the raster timestamps are overwritten.
> I haven't tried yet with absolute type.
> How should I proceed? Is there a way to avoid generating a temporary
> text file to feed register_maps_in_space_time_dataset()?
>
> Regards,
> Laurent
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