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v.db.join

Joins a database table to a vector map table.

v.db.join map=name [layer=string] column=name other_table=name other_column=name [subset_columns=name [,name,...]] [exclude_columns=name [,name,...]] [--verbose] [--quiet] [--qq] [--ui]

Example:

v.db.join map=name column=name other_table=name other_column=name

grass.script.run_command("v.db.join", map, layer="1", column, other_table, other_column, subset_columns=None, exclude_columns=None, verbose=None, quiet=None, superquiet=None)

Example:

gs.run_command("v.db.join", map="name", column="name", other_table="name", other_column="name")

grass.tools.Tools.v_db_join(map, layer="1", column, other_table, other_column, subset_columns=None, exclude_columns=None, verbose=None, quiet=None, superquiet=None)

Example:

tools = Tools()
tools.v_db_join(map="name", column="name", other_table="name", other_column="name")

This grass.tools API is experimental in version 8.5 and expected to be stable in version 8.6.

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
--help
    Print usage summary
--verbose
    Verbose module output
--quiet
    Quiet module output
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

map : str, required
    Name of vector map
    Vector map to which to join other table
    Used as: input, vector, name
layer : str, optional
    Layer number or name
    Layer where to join
    Used as: input, layer
    Default: 1
column : str, required
    Identifier column (e.g.: cat) in the vector table to be used for join
    Used as: input, dbcolumn, name
other_table : str, required
    Other table name
    Used as: input, dbtable, name
other_column : str, required
    Identifier column (e.g.: id) in the other table used for join
    Used as: input, dbcolumn, name
subset_columns : str | list[str], optional
    Subset of columns from the other table
    Used as: input, dbcolumn, name
exclude_columns : str | list[str], optional
    Columns to exclude from the other table
    Used as: input, dbcolumn, name
verbose: bool, optional
    Verbose module output
    Default: None
quiet: bool, optional
    Quiet module output
    Default: None
superquiet: bool, optional
    Very quiet module output
    Default: None

map : str, required
    Name of vector map
    Vector map to which to join other table
    Used as: input, vector, name
layer : str, optional
    Layer number or name
    Layer where to join
    Used as: input, layer
    Default: 1
column : str, required
    Identifier column (e.g.: cat) in the vector table to be used for join
    Used as: input, dbcolumn, name
other_table : str, required
    Other table name
    Used as: input, dbtable, name
other_column : str, required
    Identifier column (e.g.: id) in the other table used for join
    Used as: input, dbcolumn, name
subset_columns : str | list[str], optional
    Subset of columns from the other table
    Used as: input, dbcolumn, name
exclude_columns : str | list[str], optional
    Columns to exclude from the other table
    Used as: input, dbcolumn, name
verbose: bool, optional
    Verbose module output
    Default: None
quiet: bool, optional
    Quiet module output
    Default: None
superquiet: bool, optional
    Very quiet module output
    Default: None

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)
Latest change: Friday Feb 07 19:16:09 2025 in commit a82a39f