## DESCRIPTION

The t.merge module is designed to register the maps of several input space time datasets in a single output dataset. The datasets to merge can be either space time raster, 3D raster or vector datasets and must have the same temporal type (absolute or relative).

Existing space time datasets located in the current mapset can be specified as output as well. The maps from the input space time datasets will be added to the output.

Maps from the input space time datasets will be registered only once in the output space time dataset, hence the same maps can be registered in different input space time datasets.

## NOTES

Temporal databases stored in other mapsets can be used as long as they are in the user's current mapset search path (managed with g.mapsets).

## EXAMPLES

In this example we will create two space time raster datasets and register two unique maps in each of it. Then we merge the two space time raster datasets together.

    r.mapcalc expression="map1 = rand(0, 10)"
    r.mapcalc expression="map2 = rand(10, 20)"

    t.create type=strds temporaltype=absolute \
             output=precipitation_daily_1 \
             title="Daily precipitation" \
             description="Test dataset with daily precipitation"

    t.register -i type=raster input=precipitation_daily_1 \
               maps=map1,map2 start=2012-08-20 increment="1 days"

    t.info precipitation_daily_1

     +-------------------- Space Time Raster Dataset -----------------------------+
     |                                                                            |
     +-------------------- Basic information -------------------------------------+
     | Id: ........................ precipitation_daily_1@soeren
     | Name: ...................... precipitation_daily_1
     | Mapset: .................... soeren
     | Creator: ................... soeren
     | Temporal type: ............. absolute
     | Creation time: ............. 2014-11-23 15:26:57.395355
     | Modification time:.......... 2014-11-23 15:26:57.860513
     | Semantic type:.............. mean
     +-------------------- Absolute time -----------------------------------------+
     | Start time:................. 2012-08-20 00:00:00
     | End time:................... 2012-08-22 00:00:00
     | Granularity:................ 1 day
     | Temporal type of maps:...... interval
     +-------------------- Spatial extent ----------------------------------------+
     | North:...................... 80.0
     | South:...................... 0.0
     | East:.. .................... 120.0
     | West:....................... 0.0
     | Top:........................ 0.0
     | Bottom:..................... 0.0
     +-------------------- Metadata information ----------------------------------+
     | Raster register table:...... raster_map_register_6e6efe25ee9b40e39eb31421d737439b
     | North-South resolution min:. 10.0
     | North-South resolution max:. 10.0
     | East-west resolution min:... 10.0
     | East-west resolution max:... 10.0
     | Minimum value min:.......... 0.0
     | Minimum value max:.......... 10.0
     | Maximum value min:.......... 9.0
     | Maximum value max:.......... 19.0
     | Aggregation type:........... None
     | Number of registered maps:.. 2
     |
     | Title:
     | Daily precipitation
     | Description:
     | Test dataset with daily precipitation
     | Command history:
     | # 2014-11-23 15:26:57
     | t.create type="strds" temporaltype="absolute"
     |     output="precipitation_daily_1" title="Daily precipitation"
     |     description="Test dataset with daily precipitation"
     | # 2014-11-23 15:26:57
     | t.register -i type="rast"
     |     input="precipitation_daily_1" maps="map1,map2" start="2012-08-20"
     |     increment="1 days"
     |
     +----------------------------------------------------------------------------+

    r.mapcalc expression="map3 = rand(20, 30)"
    r.mapcalc expression="map4 = rand(30, 40)"

    t.create type=strds temporaltype=absolute \
             output=precipitation_daily_2 \
             title="Daily precipitation" \
             description="Test dataset with daily precipitation"

    t.register -i type=raster input=precipitation_daily_2 \
               maps=map3,map4 start=2012-08-22 increment="1 days"

    t.info precipitation_daily_2

     +-------------------- Space Time Raster Dataset -----------------------------+
     |                                                                            |
     +-------------------- Basic information -------------------------------------+
     | Id: ........................ precipitation_daily_2@soeren
     | Name: ...................... precipitation_daily_2
     | Mapset: .................... soeren
     | Creator: ................... soeren
     | Temporal type: ............. absolute
     | Creation time: ............. 2014-11-23 15:27:20.165074
     | Modification time:.......... 2014-11-23 15:27:20.613543
     | Semantic type:.............. mean
     +-------------------- Absolute time -----------------------------------------+
     | Start time:................. 2012-08-22 00:00:00
     | End time:................... 2012-08-24 00:00:00
     | Granularity:................ 1 day
     | Temporal type of maps:...... interval
     +-------------------- Spatial extent ----------------------------------------+
     | North:...................... 80.0
     | South:...................... 0.0
     | East:.. .................... 120.0
     | West:....................... 0.0
     | Top:........................ 0.0
     | Bottom:..................... 0.0
     +-------------------- Metadata information ----------------------------------+
     | Raster register table:...... raster_map_register_04eaede279b2476a80c2683254232f84
     | North-South resolution min:. 10.0
     | North-South resolution max:. 10.0
     | East-west resolution min:... 10.0
     | East-west resolution max:... 10.0
     | Minimum value min:.......... 20.0
     | Minimum value max:.......... 30.0
     | Maximum value min:.......... 29.0
     | Maximum value max:.......... 39.0
     | Aggregation type:........... None
     | Number of registered maps:.. 2
     |
     | Title:
     | Daily precipitation
     | Description:
     | Test dataset with daily precipitation
     | Command history:
     | # 2014-11-23 15:27:20
     | t.create type="strds" temporaltype="absolute"
     |     output="precipitation_daily_2" title="Daily precipitation"
     |     description="Test dataset with daily precipitation"
     | # 2014-11-23 15:27:20
     | t.register -i type="rast"
     |     input="precipitation_daily_2" maps="map3,map4" start="2012-08-22"
     |     increment="1 days"
     |
     +----------------------------------------------------------------------------+

    t.merge input=precipitation_daily_1,precipitation_daily_2 \
            output=precipitation_daily_3

    t.info precipitation_daily_3

     +-------------------- Space Time Raster Dataset -----------------------------+
     |                                                                            |
     +-------------------- Basic information -------------------------------------+
     | Id: ........................ precipitation_daily_3@soeren
     | Name: ...................... precipitation_daily_3
     | Mapset: .................... soeren
     | Creator: ................... soeren
     | Temporal type: ............. absolute
     | Creation time: ............. 2014-11-23 15:27:44.069272
     | Modification time:.......... 2014-11-23 15:27:44.088930
     | Semantic type:.............. mean
     +-------------------- Absolute time -----------------------------------------+
     | Start time:................. 2012-08-20 00:00:00
     | End time:................... 2012-08-24 00:00:00
     | Granularity:................ 1 day
     | Temporal type of maps:...... interval
     +-------------------- Spatial extent ----------------------------------------+
     | North:...................... 80.0
     | South:...................... 0.0
     | East:.. .................... 120.0
     | West:....................... 0.0
     | Top:........................ 0.0
     | Bottom:..................... 0.0
     +-------------------- Metadata information ----------------------------------+
     | Raster register table:...... raster_map_register_33715c8c849a43fbb9bce02e1f28ff5a
     | North-South resolution min:. 10.0
     | North-South resolution max:. 10.0
     | East-west resolution min:... 10.0
     | East-west resolution max:... 10.0
     | Minimum value min:.......... 0.0
     | Minimum value max:.......... 30.0
     | Maximum value min:.......... 9.0
     | Maximum value max:.......... 39.0
     | Aggregation type:........... None
     | Number of registered maps:.. 4
     |
     | Title:
     | Merged space time dataset
     | Description:
     | Merged space time dataset
     | Command history:
     | # 2014-11-23 15:27:44
     | t.merge
     |     input="precipitation_daily_1,precipitation_daily_2"
     |     output="precipitation_daily_3"
     |
     +----------------------------------------------------------------------------+

## SEE ALSO

t.create, t.support, t.register

## AUTHOR

Sören Gebbert, Thünen Institute of Climate-Smart Agriculture