Geografic-Information-System/temporal/t.rast.aggregate/t.rast.aggregate.html

<h2>DESCRIPTION</h2>

<em>t.rast.aggregate</em> temporally aggregates space time raster datasets by a specific temporal granularity.
This module support <em>absolute</em> and <em>relative time</em>.
The temporal granularity of absolute time can be 
<em>seconds, minutes, hours, days, weeks, months</em> or <em>years</em>.
Mixing of granularities eg. "1 year, 3 months 5 days" is not supported. 
In case of relative time the temporal unit of the input space time raster 
dataset is used. The granularity must be specified with an integer value. 
<p>
This module is sensitive to the current region and mask settings, hence spatial extent and spatial resolution. 
In case the registered raster maps of the input space time raster dataset
have different spatial resolutions, the default nearest neighbor resampling method is used for
runtime spatial aggregation.

<h2>NOTES</h2>

The raster module <em>r.series</em> is used internally. Hence all aggregate
methods of <em>r.series</em> are supported. See the <a href="r.series.html">r.series</a> manpage
for details.
<p>
This module will shift the start date for each aggregation process depending on the 
provided temporal granularity. The following shifts will performed:

<ul>
    <li><em>granularity years</em>: will start at the first of January, hence 14-08-2012 00:01:30 will be shifted to 01-01-2012 00:00:00</li>
    <li><em>granularity months</em>: will start at the first day of a month, hence 14-08-2012 will be shifted to 01-08-2012 00:00:00</li>
    <li><em>granularity weeks</em>: will start at the first day of a week (Monday), hence 14-08-2012 01:30:30 will be shifted to 13-08-2012 01:00:00</li>
    <li><em>granularity days</em>: will start at the first hour of a day, hence 14-08-2012 00:01:30 will be shifted to 14-08-2012 00:00:00</li>
    <li><em>granularity hours</em>: will start at the first minute of a hour, hence 14-08-2012 01:30:30 will be shifted to 14-08-2012 01:00:00</li>
    <li><em>granularity minutes</em>: will start at the first second of a minute, hence 14-08-2012 01:30:30 will be shifted to 14-08-2012 01:30:00</li>
</ul>

<h2>EXAMPLE</h2>

In this example we create 7 raster maps that will be registered in a single space time
raster dataset named <em>precipitation_daily</em> using a daily temporal granularity.
The names of the raster maps are stored in a text file that is used for raster map registration. 
<p>
The space time raster dataset <em>precipitation_daily</em> with daily temporal granularity 
will be aggregated to weekly precipitation resulting in the output space time raster dataset
<em>precipitation_weekly</em>. The base name of the new generated raster maps is <em>prec_weekly</em>, the
granularity is 1 week. The aggregation method is set to <em>sum</em> to accumulate the precipitation values
of all raster maps in a week. The sampling option assures that only raster maps that are 
temporally during a week will be considered for computation: 

<div class="code"><pre>

MAPS="map_1 map_2 map_3 map_4 map_5 map_6 map_7"

for map in ${MAPS} ; do
    r.mapcalc --o expr="${map} = 1" 
    echo ${map} >> map_list.txt 
done

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 \
           file=map_list.txt start="2012-08-20" increment="1 days"

t.info type=strds input=precipitation_daily

 +-------------------- Absolute time -----------------------------------------+
 | Start time:................. 2012-09-03 00:00:00
 | End time:................... 2012-09-10 00:00:00
 | Granularity:................ 1 day
 | Temporal type of maps:...... interval
 +-------------------- Spatial extent ----------------------------------------+
 | North:...................... 80.0
 | South:...................... -1.0
 | East:.. .................... 120.5
 | West:....................... -40.5
 | Top:........................ 0.0
 | Bottom:..................... 0.0
 +-------------------- Metadata information ----------------------------------+
 | Raster register table:...... precipitation_daily_test_raster_register
 | North-South resolution min:. 1.0
 | North-South resolution max:. 1.0
 | East-west resolution min:... 1.0
 | East-west resolution max:... 1.0
 | Minimum value min:.......... 1.0
 | Minimum value max:.......... 1.0
 | Maximum value min:.......... 1.0
 | Maximum value max:.......... 1.0
 | Number of registered maps:.. 7
 |
 | Title:
 | Daily precipitation
 | Description:
 | Test dataset with daily precipitation
 | Command history:
 | # 2013-07-13 13:10:46 
 | t.create type="strds" temporaltype="absolute"
 |     output="precipitation_daily" title="Daily precipitation"
 |     description="Test dataset with daily precipitation"
 | # 2013-07-13 13:10:47 
 | t.register -i type="rast" input="precipitation_daily"
 |     file="map_list.txt" start="2012-08-20" increment="1 days"
 | 
 +----------------------------------------------------------------------------+

t.rast.aggregate input=precipitation_daily \
                 output=precipitation_weekly \
                 base=prec_weekly granularity="1 weeks" \
                 method=sum sampling=during

t.support input=precipitation_weekly \
          title="Weekly precipitation" \
          description="Aggregated precipitation dataset with weekly resolution"
                 
t.info type=strds input=precipitation_weekly

 +-------------------- Space Time Raster Dataset -----------------------------+
 |                                                                            |
 +-------------------- Basic information -------------------------------------+
 | Id: ........................ precipitation_weekly@test
 | Name: ...................... precipitation_weekly
 | Mapset: .................... test
 | Creator: ................... soeren
 | Creation time: ............. 2013-07-13 13:11:23.286982
 | Temporal type: ............. absolute
 | Semantic type:.............. mean
 +-------------------- Absolute time -----------------------------------------+
 | Start time:................. 2012-09-03 00:00:00
 | End time:................... 2012-09-10 00:00:00
 | Granularity:................ 7 days
 | Temporal type of maps:...... interval
 +-------------------- Spatial extent ----------------------------------------+
 | North:...................... 80.0
 | South:...................... -1.0
 | East:.. .................... 120.5
 | West:....................... -40.5
 | Top:........................ 0.0
 | Bottom:..................... 0.0
 +-------------------- Metadata information ----------------------------------+
 | Raster register table:...... precipitation_weekly_test_raster_register
 | North-South resolution min:. 1.0
 | North-South resolution max:. 1.0
 | East-west resolution min:... 1.0
 | East-west resolution max:... 1.0
 | Minimum value min:.......... 7.0
 | Minimum value max:.......... 7.0
 | Maximum value min:.......... 7.0
 | Maximum value max:.......... 7.0
 | Number of registered maps:.. 1
 |
 | Title:
 | Weekly precipitation
 | Description:
 | Aggregated precipitation dataset with weekly resolution
 | Command history:
 | # 2013-07-13 13:11:23 
 | t.rast.aggregate input="precipitation_daily"
 |     output="precipitation_weekly" base="prec_weekly" granularity="1 weeks"
 |     method="sum" sampling="during"
 | # 2013-07-13 13:11:29 
 | t.support input="precipitation_weekly"
 |     title="Weekly precipitation"
 |     description="Aggregated precipitation dataset with weekly resolution"
 | 
 +----------------------------------------------------------------------------+
</pre></div>

<h2>SEE ALSO</h2>

<em>
<a href="t.rast.aggregate.ds.html">t.rast.aggregate.ds</a><br>
<a href="t.rast.extract.html">t.rast.extract</a><br>
<a href="t.info.html">t.info</a><br>
<a href="r.series.html">r.series</a><br>
<a href="g.region.html">g.region</a><br>
<a href="r.mask.html">r.mask</a><br>
</em>

<h2>AUTHOR</h2>

S&ouml;ren Gebbert

<p><i>Last changed: $Date$</i>