t.vect.extract.1grass - Man Page

Extracts a subset of a space time vector dataset.

t.vect.extract t.vect.extract --help t.vect.extract [-n] input=name [where=sql_query] [expression=sql_query] output=name [layer=string] [type=string[,string,...]] [basename=string] [suffix=string] [nprocs=integer] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags

-n: Register empty maps
--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

input=nameÂ [required]: Name of the input space time vector dataset
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’
expression=sql_query: WHERE conditions of SQL statement without ’where’ keyword
Example: income < 1000 and population >= 10000
output=nameÂ [required]: Name of the output space time vector dataset
layer=string: Layer number or name
Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
Default: 1
type=string[,string,...]: Input feature type
Options: point, line, boundary, centroid, area
Default: point,line,boundary,centroid,area
basename=string: Basename of the new generated output maps
A numerical suffix separated by an underscore will be attached to create a unique identifier
suffix=string: Suffix to add at basename: set ’gran’ for granularity, ’time’ for the full time format, ’num’ for numerical suffix with a specific number of digits (default %05)
Default: gran
nprocs=integer: The number of v.extract processes to run in parallel. Use only if database backend is used which supports concurrent writing
Default: 1

Description

The purpose of t.vect.extract is to extract a subset of a space time vector dataset and to store that subset in a different space time vector dataset.

Example

In the following example a new space time vector dataset will be create with all the data later than 2000:

t.vect.extract input=shoreline where="start_time > 2000" \
               output=shoreline_later_2000 basename=new_shoreline
t.info shoreline_later_2000@shoreline type=stvds
 +-------------------- Space Time Vector Dataset -----------------------------+
 |                                                                            |
 +-------------------- Basic information -------------------------------------+
 | Id: ........................ shoreline_later_2000@shoreline
 | Name: ...................... shoreline_later_2000
 | Mapset: .................... shoreline
 | Creator: ................... lucadelu
 | Temporal type: ............. relative
 | Creation time: ............. 2014-11-29 08:43:50.043219
 | Modification time:.......... 2014-11-29 08:43:50.085407
 | Semantic type:.............. mean
 +-------------------- Relative time -----------------------------------------+
 | Start time:................. 2003
 | End time:................... 2009
 | Relative time unit:......... years
 | Granularity:................ 1
 | Temporal type of maps:...... point
 +-------------------- Spatial extent ----------------------------------------+
 | North:...................... 1039175.31479
 | South:...................... 34705.216018
 | East:.. .................... 3052322.44671
 | West:....................... 2130004.16779
 | Top:........................ 0.0
 | Bottom:..................... 0.0
 +-------------------- Metadata information ----------------------------------+
 | Vector register table:...... vector_map_register_8395740fc8de42149fef74a3d25bbb05
 | Number of points ........... 0
 | Number of lines ............ 407
 | Number of boundaries ....... 0
 | Number of centroids ........ 0
 | Number of faces ............ 0
 | Number of kernels .......... 0
 | Number of primitives ....... 407
 | Number of nodes ............ 767
 | Number of areas ............ 0
 | Number of islands .......... 0
 | Number of holes ............ 0
 | Number of volumes .......... 0
 | Number of registered maps:.. 3
 |
 | Title:
 | North Carolina shoreline
 | Description:
 | North Caroline shoreline from 2000 to 2009
 | Command history:
 | # 2014-11-29 08:43:50
 | t.vect.extract input="shoreline"
 |     where="start_time > 2000" output="shoreline_later_2000"
 |     basename="new_shoreline"
 | # 2014-11-29 08:44:14
 | t.support type="stvds"
 |     input="shoreline_later_2000@shoreline"
 |     descr="North Caroline shoreline from 2000 to 2009"
 +----------------------------------------------------------------------------+
t.vect.list shoreline_later_2000
name|layer|mapset|start_time|end_time
shoreline_2003|None|shoreline|2003|None
shoreline_2004|None|shoreline|2004|None
shoreline_2009|None|shoreline|2009|None