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t.rast.what(1)		    GRASS GIS User's Manual		t.rast.what(1)

NAME
       t.rast.what   -	Sample	a space	time raster dataset at specific	vector
       point coordinates and write the output to stdout	using  different  lay-
       outs

KEYWORDS
       temporal, sampling, raster, time

SYNOPSIS
       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]

   Flags:
       -n
	   Output header row

       -i
	   Use stdin as	input and ignore coordinates and point option

       -v
	   Show	the category for vector	points map

       --overwrite
	   Allow output	files to overwrite existing files

       --help
	   Print usage summary

       --verbose
	   Verbose module output

       --quiet
	   Quiet module	output

       --ui
	   Force launching GUI dialog

   Parameters:
       points=name
	   Name	of input vector	map
	   Or data source for direct OGR access

       coordinates=east,north
	   Comma separated list	of coordinates

       strds=nameA [required]
	   Name	of the input space time	raster dataset

       output=name
	   Name	for the	output file or "-" in case stdout should be used
	   Default: -

       where=sql_query
	   WHERE  conditions  of SQL statement without 'where' keyword used in
	   the temporal	GIS framework
	   Example: start_time > '2001-01-01 12:30:00'

       null_value=string
	   String representing NULL value

       separator=character
	   Field separator
	   Special characters: pipe, comma, space, tab,	newline
	   Default: pipe

       order=string[,string,...]
	   Sort	the maps by category
	   Options: id,	 name,	creator,  mapset,   creation_time,   modifica-
	   tion_time,	start_time,   end_time,	  north,  south,  west,	 east,
	   min,	 max
	   Default: start_time

       layout=string
	   The layout of the output. One point per row (row),  one  point  per
	   column (col), all timsteps in one row (timerow)
	   Options: row,  col,	timerow
	   Default: row

       nprocs=integer
	   Number of r.what processes to run in	parallel
	   Default: 1

DESCRIPTION
       t.rast.what  is	designed  to sample space time raster datasets at spe-
       cific 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:

	   o   row - Row order,	one vector sample point	value per row

	   o   col - Column order, create a  column  for  each	vector	sample
	       point of	a single time step/raster layer

	   o   timerow	- Time order, create a column for each time step, this
	       order is	the original r.what output,  except  that  the	column
	       names are the timestamps
       Please have a look at the example to see	the supported layouts.

       This  module  is	 designed to run several instances of r.what to	sample
       subsets of a space time raster dataset in parallel. Several  intermedi-
       ate  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
       "-".

EXAMPLES
   Data	preparation
       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"

   Example 1
       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

   Example 2
       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

SEE ALSO
	 g.region,  r.mask  r.neighbors,  r.what, t.info, t.rast.aggregate.ds,
       t.rast.extract, v.what.strds

AUTHOR
       SA<paragraph>ren	Gebbert, ThA1/4nen Institute of	Climate-Smart Agricul-
       ture

SOURCE CODE
       Available at: t.rast.what source	code (history)

       Main index | Temporal index | Topics index | Keywords index | Graphical
       index | Full index

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.4 Reference	Manual

GRASS 7.8.4							t.rast.what(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | AUTHOR | SOURCE CODE

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