This module is useful to analyze temporal relationships between space time datasets using temporal topology. The flag -s enables a spatio-temporal topology, so that only spatio-temporal related map layers of space time datasets are considered in the analysis.
The textual output at the command line shows the names of the maps, start and end time as well as the interval length in days and the temporal distance from begin in days.
The default separator is the pipe symbol.
Temporal gaps, if present, in the input and sampling space time datasets will be used in the sampling process. Gaps have no map name, instead None is printed.
We use t.sample to inspect the topological relations between the time stamped map layers in A and P.
# Set an appropriate region g.region s=0 n=80 w=0 e=120 b=0 t=50 res=10 res3=10 -p3 # Generate the raster map layer r.mapcalc expression="a1 = rand(0, 550)" -s r.mapcalc expression="a2 = rand(0, 450)" -s r.mapcalc expression="a3 = rand(0, 320)" -s r.mapcalc expression="a4 = rand(0, 510)" -s r.mapcalc expression="a5 = rand(0, 300)" -s r.mapcalc expression="a6 = rand(0, 650)" -s # Generate the vector map layer v.random -z output=pnts1 n=20 zmin=0 zmax=100 column=height v.random -z output=pnts2 n=20 zmin=0 zmax=100 column=height n1=`g.tempfile pid=1 -d` n2=`g.tempfile pid=2 -d` cat > "${n1}" << EOF a1 a2 a3 a4 a5 a6 EOF cat > "${n2}" << EOF pnts1|2001-01-01|2001-03-01 pnts2|2001-05-01|2001-07-01 EOF # Register the maps in new space time datasets t.create type=strds temporaltype=absolute output=A \ title="A test with raster input files" descr="A test with raster input files" t.create type=stvds temporaltype=absolute output=P \ title="A test with vector input files" descr="A test with vector input files" t.register type=raster -i input=A file="${n1}" start="2001-01-01" increment="1 months" # Raster map layer in A t.rast.list A name|mapset|start_time|end_time a1|PERMANENT|2001-01-01 00:00:00|2001-02-01 00:00:00 a2|PERMANENT|2001-02-01 00:00:00|2001-03-01 00:00:00 a3|PERMANENT|2001-03-01 00:00:00|2001-04-01 00:00:00 a4|PERMANENT|2001-04-01 00:00:00|2001-05-01 00:00:00 a5|PERMANENT|2001-05-01 00:00:00|2001-06-01 00:00:00 a6|PERMANENT|2001-06-01 00:00:00|2001-07-01 00:00:00 t.register type=vector input=P file="${n2}" # Vector map layer in P t.vect.list P name|layer|mapset|start_time|end_time pnts1|None|PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00 pnts2|None|PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00 # Start time of maps in A located in maps in P t.sample method=start input=A samtype=stvds sample=P -c P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin pnts1@PERMANENT|a1@PERMANENT,a2@PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0 None|a3@PERMANENT,a4@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0 pnts2@PERMANENT|a5@PERMANENT,a6@PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0 # P contains A t.sample method=contain input=A samtype=stvds sample=P -c P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin pnts1@PERMANENT|a1@PERMANENT,a2@PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0 None|a3@PERMANENT,a4@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0 pnts2@PERMANENT|a5@PERMANENT,a6@PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0 # A during P t.sample method=during intype=stvds input=P samtype=strds sample=A -c A@PERMANENT|P@PERMANENT|start_time|end_time|interval_length|distance_from_begin a1@PERMANENT|pnts1@PERMANENT|2001-01-01 00:00:00|2001-02-01 00:00:00|31.0|0.0 a2@PERMANENT|pnts1@PERMANENT|2001-02-01 00:00:00|2001-03-01 00:00:00|28.0|31.0 a3@PERMANENT|None|2001-03-01 00:00:00|2001-04-01 00:00:00|31.0|59.0 a4@PERMANENT|None|2001-04-01 00:00:00|2001-05-01 00:00:00|30.0|90.0 a5@PERMANENT|pnts2@PERMANENT|2001-05-01 00:00:00|2001-06-01 00:00:00|31.0|120.0 a6@PERMANENT|pnts2@PERMANENT|2001-06-01 00:00:00|2001-07-01 00:00:00|30.0|151.0 # No Overlapping t.sample method=overlap input=A samtype=stvds sample=P -cs P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin pnts1@PERMANENT|None|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0 None|None|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0 pnts2@PERMANENT|None|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0 t.sample method=precedes input=A samtype=stvds sample=P -c P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin pnts1@PERMANENT|a3@PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0 None|a5@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0 pnts2@PERMANENT|None|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0 t.sample method=follows input=A samtype=stvds sample=P -c P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin pnts1@PERMANENT|None|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0 None|a2@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0 pnts2@PERMANENT|a4@PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0 t.sample method=precedes,follows input=A samtype=stvds sample=P -c P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin pnts1@PERMANENT|a3@PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0 None|a5@PERMANENT,a2@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0 pnts2@PERMANENT|a4@PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0
Available at: t.sample source code (history)
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