DESCRIPTION

t.shift is designed to temporally shift all registered maps in a space time dataset with a user defined granularity. Raster, 3D raster and vector space time datasets are supported.

The format of the absolute time granularity is "number unit". Number is an integer, unit is the temporal unit that can be one of year(s), month(s), week(s), day(s), hour(s), minute(s) or second(s).

The granularity in case of relative time is an integer. The temporal unit is the unit of the space time dataset and can not be modified.

Note

Be careful when shifting space time datasets with absolute time. The temporal granularity may change if you shift a space time dataset with a unit that is different from the space time dataset granularity. Be aware that the shifting with months and years may result in incorrect days per month. Shifting the date 20012-03-31 with a granularity of one month will result in 2012-04-31 which is incorrect. In this case an error will raise and the shifting will not performed for the whole dataset.

You can use the extraction module to shift only a subset of maps from a space time dataset. Be aware that the shifting of maps affect all space time datasets in which they are registered.

EXAMPLE

We create 6 raster maps and register them in a space time raster dataset using an increment of one day. Then we shift the time intervals with a granularity of 12 hours. 

r.mapcalc expr="prec_1 = rand(0, 550)"
r.mapcalc expr="prec_2 = rand(0, 450)"
r.mapcalc expr="prec_3 = rand(0, 320)"
r.mapcalc expr="prec_4 = rand(0, 510)"
r.mapcalc expr="prec_5 = rand(0, 300)"
r.mapcalc expr="prec_6 = rand(0, 650)"

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

t.register -i type=rast input=precipitation_daily \
           maps=prec_1,prec_2,prec_3,prec_4,prec_5,prec_6 \
           start=2012-01-01 increment="1 day"

t.info type=strds input=precipitation_daily

 +-------------------- Space Time Raster Dataset -----------------------------+
 |                                                                            |
 +-------------------- Basic information -------------------------------------+
 | Id: ........................ precipitation_daily@soeren
 | Name: ...................... precipitation_daily
 | Mapset: .................... soeren
 | Creator: ................... soeren
 | Creation time: ............. 2013-04-20 14:41:55.392394
 | Temporal type: ............. absolute
 | Semantic type:.............. mean
 +-------------------- Absolute time -----------------------------------------+
 | Start time:................. 2012-01-01 00:00:00
 | End time:................... 2012-01-07 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 ----------------------------------+
 | Number of registered maps:.. 6
 | Title:
 | Daily precipitation
 | Description:
 | Test dataset with daily precipitation
 | Commands of creation:
 | - 2013-04-20 14:41:55 -
 | t.create type="strds" temporaltype="absolute"
 |     output="precipitation_daily" title="Daily precipitation"
 |     description="Test dataset with daily precipitation"
 | - 2013-04-20 14:41:55 -
 | t.register -i type="rast"
 |     input="precipitation_daily"
 |     maps="prec_1,prec_2,prec_3,prec_4,prec_5,prec_6" start="2012-01-01"
 |     increment="1 day"
 | 
 | 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:.......... 0.0
 | Maximum value min:.......... 296.0
 | Maximum value max:.......... 648.0
 | Raster register table:...... precipitation_daily_soeren_raster_register
 +----------------------------------------------------------------------------+
 
t.rast.list input=precipitation_daily

prec_1  soeren  2012-01-01 00:00:00 2012-01-02 00:00:00
prec_2  soeren  2012-01-02 00:00:00 2012-01-03 00:00:00
prec_3  soeren  2012-01-03 00:00:00 2012-01-04 00:00:00
prec_4  soeren  2012-01-04 00:00:00 2012-01-05 00:00:00
prec_5  soeren  2012-01-05 00:00:00 2012-01-06 00:00:00
prec_6  soeren  2012-01-06 00:00:00 2012-01-07 00:00:00

t.shift type=strds input=precipitation_daily granularity="12 hours"

t.info type=strds input=precipitation_daily

 +-------------------- Space Time Raster Dataset -----------------------------+
 |                                                                            |
 +-------------------- Basic information -------------------------------------+
 | Id: ........................ precipitation_daily@soeren
 | Name: ...................... precipitation_daily
 | Mapset: .................... soeren
 | Creator: ................... soeren
 | Creation time: ............. 2013-04-20 14:41:55.392394
 | Temporal type: ............. absolute
 | Semantic type:.............. mean
 +-------------------- Absolute time -----------------------------------------+
 | Start time:................. 2012-01-01 12:00:00
 | End time:................... 2012-01-07 12:00:00
 | Granularity:................ 24 hours
 | 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 ----------------------------------+
 | Number of registered maps:.. 6
 | Title:
 | Daily precipitation
 | Description:
 | Test dataset with daily precipitation
 | Commands of creation:
 | - 2013-04-20 14:41:55 -
 | t.create type="strds" temporaltype="absolute"
 |     output="precipitation_daily" title="Daily precipitation"
 |     description="Test dataset with daily precipitation"
 | - 2013-04-20 14:41:55 -
 | t.register -i type="rast"
 |     input="precipitation_daily"
 |     maps="prec_1,prec_2,prec_3,prec_4,prec_5,prec_6" start="2012-01-01"
 |     increment="1 day"
 | - 2013-04-20 14:42:21 -
 | t.shift type="strds" input="precipitation_daily"
 |     granularity="12 hours"
 | 
 | 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:.......... 0.0
 | Maximum value min:.......... 296.0
 | Maximum value max:.......... 648.0
 | Raster register table:...... precipitation_daily_soeren_raster_register
 +----------------------------------------------------------------------------+

t.rast.list input=precipitation_daily

prec_1  soeren  2012-01-01 12:00:00 2012-01-02 12:00:00
prec_2  soeren  2012-01-02 12:00:00 2012-01-03 12:00:00
prec_3  soeren  2012-01-03 12:00:00 2012-01-04 12:00:00
prec_4  soeren  2012-01-04 12:00:00 2012-01-05 12:00:00
prec_5  soeren  2012-01-05 12:00:00 2012-01-06 12:00:00
prec_6  soeren  2012-01-06 12:00:00 2012-01-07 12:00:00

SEE ALSO

t.create, t.register, t.snap

AUTHOR

Sören Gebbert

Last changed: $Date$