v.net.curvedarcs

Draws curved arcs between points (e.g. flows)

v.net.curvedarcs [-s] input=name [layer=string] flow_input_file=name [separator=character] output=name minimum_offset=float maximum_offset=float [vertices=integer] [--overwrite] [--verbose] [--quiet] [--qq] [--ui]

Example:

v.net.curvedarcs input=name flow_input_file=name output=name minimum_offset=float maximum_offset=float

grass.script.run_command("v.net.curvedarcs", input, layer="1", flow_input_file, separator="pipe", output, minimum_offset, maximum_offset, vertices=30, flags=None, overwrite=False, verbose=False, quiet=False, superquiet=False)

Example:

gs.run_command("v.net.curvedarcs", input="name", flow_input_file="name", output="name", minimum_offset=float, maximum_offset=float)

Parameters

Command linePython (grass.script)

input=name [required]
    Point map containing origins and destinations
    Or data source for direct OGR access
layer=string
    Layer number where to find point categories
    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
flow_input_file=name [required]
    File containing origins, destinations and flow volumes
    Name of input file
separator=character
    Separator used in input text file
    Special characters: pipe, comma, space, tab, newline
    Default: pipe
output=name [required]
    Output map with curved lines
    Name for output vector map
minimum_offset=float [required]
    minimum offset at furthest point from straight line
maximum_offset=float [required]
    maximum offset at furthest point from straight line
vertices=integer
    number of vertices used to draw curved lines
    Default: 30
-s
    Draw also short line for flow from and to same node
--overwrite
    Allow output files to overwrite existing files
--help
    Print usage summary
--verbose
    Verbose module output
--quiet
    Quiet module output
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

input : str, required
    Point map containing origins and destinations
    Or data source for direct OGR access
    Used as: input, vector, name
layer : str, optional
    Layer number where to find point categories
    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.
    Used as: input, layer
    Default: 1
flow_input_file : str, required
    File containing origins, destinations and flow volumes
    Name of input file
    Used as: input, file, name
separator : str, optional
    Separator used in input text file
    Special characters: pipe, comma, space, tab, newline
    Used as: input, separator, character
    Default: pipe
output : str, required
    Output map with curved lines
    Name for output vector map
    Used as: output, vector, name
minimum_offset : float, required
    minimum offset at furthest point from straight line
maximum_offset : float, required
    maximum offset at furthest point from straight line
vertices : int, optional
    number of vertices used to draw curved lines
    Default: 30
flags : str, optional
    Allowed values: s
    s
        Draw also short line for flow from and to same node
overwrite: bool, optional
    Allow output files to overwrite existing files
    Default: False
verbose: bool, optional
    Verbose module output
    Default: False
quiet: bool, optional
    Quiet module output
    Default: False
superquiet: bool, optional
    Very quiet module output
    Default: False

DESCRIPTION

v.net.curvedarcs is a frontend to v.net and v.segment that creates curved arcs between given start and end points. The user provides a point vector map and a text file (see Notes section) with start and end point categories as well as a flow volume for this link which will be transferred to the attribute table of the curved arcs.

The user can determine the nature of the curve with the minimum_offset and maximum_offset parameters. The longest curve's maximum offset from a straight line is equal to the value of maximum_offset in map units. The other curves maximum offset from a straight line is calulated as length(x)/max_length * max_offset. In other words, shorter lines are less curved than longer lines. However, any line's maximum offset is always at least minimum_offset from the straight line.

NOTES

EXAMPLE

TODO

v.extract census_wake2000 cat=1,52,70,99,101 type=centroid out=tmp
v.type tmp from=centroid to=point out=points
echo >> flows.txt << EOF
> from,to,volume
> 52,1,100
> 1,52,50
> 70,1,50
> 1,70,50
> 99,1,66
> 1,99,100
> 101,1,25
> 1,101,75
> EOF
v.net.curvedarcs in=points flow=flows.txt sep=comma out=flows minoff=0 maxoff=2000
d.vect map=flows display=shape,dir width_column=volume width_scale=0.05 size=10
d.vect map=points display=shape,cat fill_color=red icon=basic/circle label_bcolor=black label_size=12 yref=bottom

The curved arcs with minimum offset = 150 and maximum offset = 2000

Using different amount of curvature:

v.net.curvedarcs in=points flow=flows.txt sep=comma out=flows minoff=150 maxoff=5000 --o
d.vect map=flows display=shape,dir width_column=volume width_scale=0.05 size=10
d.vect map=points display=shape,cat fill_color=red icon=basic/circle label_bcolor=black label_size=12 yref=bottom

The curved arcs with minimum offset = 0 and maximum offset = 5000

AUTHOR

Moritz Lennert, DGES-ULB

SOURCE CODE

Available at: v.net.curvedarcs source code (history)
Latest change: Thursday Feb 20 13:02:26 2025 in commit 53de819