table of contents
v.db.join(1grass) | GRASS GIS User's Manual | v.db.join(1grass) |
NAME¶
v.db.join - Joins a database table to a vector map table.
KEYWORDS¶
vector, attribute table, database
SYNOPSIS¶
v.db.join
v.db.join --help
v.db.join map=name [layer=string]
column=name other_table=name
other_column=name
[subset_columns=name[,name,...]]
[exclude_columns=name[,name,...]] [--help]
[--verbose] [--quiet] [--ui]
Flags:¶
Parameters:¶
- map=name [required]
-
Name of vector map
Vector map to which to join other table - layer=string
-
Layer number or name
Layer where to join
Default: 1 - column=name [required]
-
Identifier column (e.g.: cat) in the vector table to be used for join - other_table=name [required]
-
Other table name - other_column=name [required]
-
Identifier column (e.g.: id) in the other table used for join - subset_columns=name[,name,...]
-
Subset of columns from the other table - exclude_columns=name[,name,...]
-
Columns to exclude from the other table
DESCRIPTION¶
v.db.join joins the content of another table into the connected attribute table of a vector map.
NOTES¶
v.db.join is a front-end to db.execute to allow easier usage. The vector attribute table must be stored in a SQL database (SQLite, PostgreSQL, MySQL, ODBC, ...). The DBF backend is not supported. Tables can be imported with db.in.ogr.
The vector map-database connection(s) can be verified with v.db.connect.
EXAMPLES¶
Exercise to join North Carolina geological classes from a CSV
table to the "geology" map of the North Carolina sample dataset
(requires download of legend CSV file nc_geology.csv from External data for
NC sample dataset):
# check original map attributes v.db.select geology column=GEO_NAME,SHAPE_area # import of CSV table db.in.ogr input=nc_geology.csv output=nc_geology # work on copy of geology map in current mapset g.copy vector=geology,mygeology # check column names of vector map attributes v.info -c mygeology # check column names of legend table db.describe -c nc_geology # join table using key columns (map: "GEO_NAME"; table: "geol_id") v.db.join map=mygeology column=GEO_NAME other_table=nc_geology other_column=geol_id # verify result (here abbreviated) v.db.select mygeology | head -3 cat|onemap_pro|PERIMETER|GEOL250_|GEOL250_ID|GEO_NAME|SHAPE_area|SHAPE_len|geol_id|longname|comment 1|963738.75|4083.97998|2|1|Zml|963738.608571|4083.979839|Zml|Metagraywacke|Interlayered with metaconglomerate, ... 2|22189124|26628.261719|3|2|Zmf|22189123.2296|26628.261112|Zmf|Metafelsite|Light-colored porphyritic extrusive rock ...
Soil map table join¶
Joining the soil type explanations from table soils_legend
into the Spearfish soils map (download legend):
g.copy vect=soils,mysoils # import legend table db.in.ogr soils_legend.csv out=soils_legend # get join column names v.info -c mysoils db.describe -c soils_legend # look at original table v.db.select mysoils cat|label 1|Aab 2|Ba 3|Bb 4|BcB 5|BcC ... # look at legend db.select table=soils_legend db.select table=soils_legend | head -7 id|shortname|longname 0|no data|no data 0|AaB|Alice fine sandy loam, 0 to 6 0|Ba|Barnum silt loam 0|Bb|Barnum silt loam, channeled 0|BcB|Boneek silt loam, 2 to 6 0|BcC|Boneek silt loam, 6 to 9 ... # join soils_legend into mysoils attribute table v.db.join mysoils col=label other_table=soils_legend ocol=shortname # verification of join v.db.select mysoils cat|label|id|shortname|longname 1|Aab||| 2|Ba|2|Ba|Barnum silt loam 3|Bb|3|Bb|Barnum silt loam, channeled 4|BcB|4|BcB|Boneek silt loam, 2 to 6 5|BcC|5|BcC|Boneek silt loam, 6 to 9 ...
SEE ALSO¶
db.execute, db.in.ogr, db.select, v.db.update
GRASS SQL interface
AUTHOR¶
Markus Neteler
SOURCE CODE¶
Available at: v.db.join source code (history)
Accessed: Saturday Jul 27 17:09:13 2024
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