t.rast.what(1grass) | Grass User's Manual | t.rast.what(1grass) |
t.rast.what - Sample a space time raster dataset at specific vector point coordinates and write the output to stdout using different layouts
temporal, sampling, raster, time
t.rast.what
t.rast.what --help
t.rast.what [-niv] [points=name]
[coordinates=east,north] strds=name
[output=name] [where=sql_query]
[null_value=string] [separator=character]
[order=string[,string,...]]
[layout=string] [nprocs=integer]
[--overwrite] [--help] [--verbose] [--quiet]
[--ui]
t.rast.what is designed to sample space time raster datasets at specific point coordinates using r.what internally. The output of r.what is transformed to different output layouts. The output layouts can be specified using the layout option.
Three layouts can be specified:
This module is designed to run several instances of r.what to sample subsets of a space time raster dataset in parallel. Several intermediate text files will be created that are merged into a single file at the end of the processing.
Coordinates can be provided as vector map using the points option or as comma separated coordinate list with the coordinates option.
An output file can be specified using the output option. Stdout will be used if no output is specified or if the output option is set to "-".
In the following examples we sample a space time raster dataset
that contains 4 raster map layers. First we create the STRDS that will be
sampled with t.rast.what.
g.region s=0 n=80 w=0 e=120 b=0 t=50 res=10 # Generate data r.mapcalc expression="a_1 = 1" -s r.mapcalc expression="a_2 = 2" -s r.mapcalc expression="a_3 = 3" -s r.mapcalc expression="a_4 = 4" -s t.create type=strds output=A title="A test" descr="A test" t.register -i type=raster input=A maps=a_1,a_2,a_3,a_4 \
start=’1990-01-01’ increment="1 month"
The first approach uses text coordinates as input and stdout as
output, the layout is one coordinate(point per column:
t.rast.what strds=A coordinates="115,36,79,45" layout=col -n start|end|115.0000000000;36.0000000000|79.0000000000;45.0000000000 1990-01-01 00:00:00|1990-02-01 00:00:00|1|1 1990-02-01 00:00:00|1990-03-01 00:00:00|2|2 1990-03-01 00:00:00|1990-04-01 00:00:00|3|3 1990-04-01 00:00:00|1990-05-01 00:00:00|4|4
A vector map layer can be used as input to sample the STRDS. All
three available layouts are demonstrated using the vector map for sampling.
# First create the vector map layer based on random points v.random output=points n=3 seed=1 # Row layout using a text file as output t.rast.what strds=A points=points output=result.txt layout=row -n cat result.txt 115.0043586274|36.3593955783|1990-01-01 00:00:00|1990-02-01 00:00:00|1 115.0043586274|36.3593955783|1990-02-01 00:00:00|1990-03-01 00:00:00|2 115.0043586274|36.3593955783|1990-03-01 00:00:00|1990-04-01 00:00:00|3 115.0043586274|36.3593955783|1990-04-01 00:00:00|1990-05-01 00:00:00|4 79.6816763826|45.2391522853|1990-01-01 00:00:00|1990-02-01 00:00:00|1 79.6816763826|45.2391522853|1990-02-01 00:00:00|1990-03-01 00:00:00|2 79.6816763826|45.2391522853|1990-03-01 00:00:00|1990-04-01 00:00:00|3 79.6816763826|45.2391522853|1990-04-01 00:00:00|1990-05-01 00:00:00|4 97.4892579600|79.2347263950|1990-01-01 00:00:00|1990-02-01 00:00:00|1 97.4892579600|79.2347263950|1990-02-01 00:00:00|1990-03-01 00:00:00|2 97.4892579600|79.2347263950|1990-03-01 00:00:00|1990-04-01 00:00:00|3 97.4892579600|79.2347263950|1990-04-01 00:00:00|1990-05-01 00:00:00|4 # Column layout order using stdout as output t.rast.what strds=A points=points layout=col -n start|end|115.0043586274;36.3593955783|79.6816763826;45.2391522853|97.4892579600;79.2347263950 1990-01-01 00:00:00|1990-02-01 00:00:00|1|1|1 1990-02-01 00:00:00|1990-03-01 00:00:00|2|2|2 1990-03-01 00:00:00|1990-04-01 00:00:00|3|3|3 1990-04-01 00:00:00|1990-05-01 00:00:00|4|4|4 # Timerow layout, one time series per row # using the where statement to select a subset of the STRDS # and stdout as output t.rast.what strds=A points=points \
where="start_time >= ’1990-03-01’" layout=timerow -n x|y|1990-03-01 00:00:00;1990-04-01 00:00:00|1990-04-01 00:00:00;1990-05-01 00:00:00 115.004358627375|36.3593955782903|3|4 79.681676382576|45.2391522852909|3|4 97.4892579600048|79.2347263950131|3|4
g.region, r.mask r.neighbors, r.what, t.info, t.rast.aggregate.ds, t.rast.extract, v.what.strds
Sören Gebbert, Thünen Institute of Climate-Smart Agriculture
Last changed: $Date: 2015-09-25 13:07:25 +0200 (Fri, 25 Sep 2015) $
Available at: t.rast.what source code (history)
Main index | Temporal index | Topics index | Keywords index | Graphical index | Full index
© 2003-2019 GRASS Development Team, GRASS GIS 7.6.0 Reference Manual
GRASS 7.6.0 |