Network analysis
================
.. only:: html
.. contents::
:local:
:depth: 1
.. _qgisserviceareafromlayer:
Service area (from layer)
-------------------------
Returns all the edges or parts of edges of a network that can be
reached within a distance or a time, starting from a point layer.
This allows evaluation of accessibility within a network, e.g. what
are the places I can navigate to on a road network without spending
cost greater than a given value (the cost can be distance or time).
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Vector layer representing network**
- ``INPUT``
- [vector: line]
- Line vector layer representing the network to be covered
* - **Vector layer with start points**
- ``START_POINTS``
- [vector: point]
- Point vector layer whose features are used as start points
to generate the service areas
* - **Path type to calculate**
- ``STRATEGY``
- [enumeration]
Default: 0
- The type of path to calculate. One of:
* 0 --- Shortest
* 1 --- Fastest
* - **Travel cost (distance for "Shortest", time for "Fastest")**
- ``TRAVEL_COST``
- [number]
Default: 0
- The value is estimated as a distance (in the network
layer units) when looking for the *Shortest* path and
as time (in hours) for the *Fastest* path.
* - **Service area (lines)**
- ``OUTPUT_LINES``
- [vector: line]
Default: ``[Create temporary layer]``
- Specify the output line layer for the service area.
One of:
.. include:: ../algs_include.rst
:start-after: **layer_output_types_skip**
:end-before: **end_layer_output_types_skip**
* - **Service area (boundary nodes)**
- ``OUTPUT``
- [vector: point]
Default: ``[Skip output]``
- Specify the output point layer for the service area
boundary nodes. One of:
.. include:: ../algs_include.rst
:start-after: **layer_output_types_skip**
:end-before: **end_layer_output_types_skip**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. **network_advanced_parameters**
.. This section is included in the network analysis algorithms
qgisserviceareafrompoint, qgisserviceareafromlayer,
qgisshortestpathlayertopoint, qgisshortestpathpointtolayer, qgisshortestpathpointtopoint
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Direction field**
Optional
- ``DIRECTION_FIELD``
- [tablefield: string]
Default: 0.0
- The field used to specify directions for the network edges.
The values used in this field are specified with the three
parameters ``Value for forward direction``,
``Value for backward direction`` and
``Value for both directions``.
Forward and reverse directions correspond to a one-way edge,
"both directions" indicates a two-way edge.
If a feature does not have a value in this field, or no field
is set then the default direction setting (provided with
the ``Default direction`` parameter) is used.
* - **Value for forward direction**
Optional
- ``VALUE_FORWARD``
- [string]
Default: '' (empty string)
- Value set in the direction field to identify edges with a
forward direction
* - **Value for backward direction**
Optional
- ``VALUE_BACKWARD``
- [string]
Default: '' (empty string)
- Value set in the direction field to identify edges with a
backward direction
* - **Value for both directions**
Optional
- ``VALUE_BOTH``
- [string]
Default: '' (empty string)
- Value set in the direction field to identify
bidirectional edges
* - **Default direction**
- ``DEFAULT_DIRECTION``
- [enumeration]
Default: 2
- If a feature has no value set in the direction field or
if no direction field is set, then this direction value
is used. One of:
* 0 --- Forward direction
* 1 --- Backward direction
* 2 --- Both directions
* - **Speed field**
Optional
- ``SPEED_FIELD``
- [tablefield: string]
- Field providing the speed value (in ``km/h``) for the
edges of the network when looking for the fastest path.
If a feature does not have a value in this field, or
no field is set then the default speed value (provided
with the ``Default speed`` parameter) is used.
* - **Default speed (km/h)**
- ``DEFAULT_SPEED``
- [number]
Default: 50.0
- Value to use to calculate the travel time if no speed
field is provided for an edge
* - **Topology tolerance**
- ``TOLERANCE``
- [number]
Default: 0.0
- Two lines with nodes closer than the specified
tolerance are considered connected
.. **end_network_advanced_parameters**
.. list-table::
:widths: 20 20 20 40
* - **Include upper/lower bound points**
- ``INCLUDE_BOUNDS``
- [boolean]
Default: False
- Creates a point layer output with two points for each
edge at the boundaries of the service area.
One point is the start of that edge, the other is the end.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Service area (boundary nodes)**
- ``OUTPUT``
- [vector: point]
- The output point layer with the service area boundary
nodes.
* - **Service area (lines)**
- ``OUTPUT_LINES``
- [vector: line]
- Line layer representing the parts of the network
that can be serviced by the start points, for the
given cost.
Python code
...........
**Algorithm ID**: ``qgis:serviceareafromlayer``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _qgisserviceareafrompoint:
Service area (from point)
-------------------------
Returns all the edges or parts of edges of a network that can be
reached within a given distance or time, starting from a point
feature.
This allows the evaluation of accessibility within a network, e.g.
what are the places I can navigate to on a road network without
spending a cost greater than a given value (the cost can be distance
or time).
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Vector layer representing the network**
- ``INPUT``
- [vector: line]
- Line vector layer representing the network to be covered
* - **Start point (x, y)**
- ``START_POINT``
- [coordinates]
- Coordinate of the point to calculate the service
area around.
* - **Path type to calculate**
- ``STRATEGY``
- [enumeration]
Default: 0
- The type of path to calculate. One of:
* 0 --- Shortest
* 1 --- Fastest
* - **Travel cost (distance for "Shortest", time for "Fastest")**
- ``TRAVEL_COST``
- [number]
Default: 0
- The value is estimated as a distance (in the network
layer units) when looking for the *Shortest* path and
as time (in hours) for the *Fastest* path.
* - **Service area (lines)**
- ``OUTPUT_LINES``
- [vector: line]
Default: ``[Create temporary layer]``
- Specify the output line layer for the service area.
One of:
.. include:: ../algs_include.rst
:start-after: **layer_output_types_skip**
:end-before: **end_layer_output_types_skip**
* - **Service area (boundary nodes)**
- ``OUTPUT``
- [vector: point]
Default: ``[Skip output]``
- Specify the output point layer for the service area
boundary nodes. One of:
.. include:: ../algs_include.rst
:start-after: **layer_output_types_skip**
:end-before: **end_layer_output_types_skip**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. include:: ./networkanalysis.rst
:start-after: .. **network_advanced_parameters**
:end-before: .. **end_network_advanced_parameters**
.. list-table::
:widths: 20 20 20 40
* - **Include upper/lower bound points**
- ``INCLUDE_BOUNDS``
- [boolean]
Default: False
- Creates a point layer output with two points for each
edge at the boundaries of the service area.
One point is the start of that edge, the other is the end.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Service area (boundary nodes)**
- ``OUTPUT``
- [vector: point]
- The output point layer with the service area boundary
nodes.
* - **Service area (lines)**
- ``OUTPUT_LINES``
- [vector: line]
- Line layer representing the parts of the network
that can be serviced by the start point, for the
given cost.
Python code
...........
**Algorithm ID**: ``native:serviceareafrompoint``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _qgisshortestpathlayertopoint:
Shortest path (layer to point)
------------------------------
Computes the optimal (shortest or fastest) routes from multiple start
points defined by a vector layer and a given end point.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Vector layer representing network**
- ``INPUT``
- [vector: line]
- Line vector layer representing the network to be covered
* - **Path type to calculate**
- ``STRATEGY``
- [enumeration]
Default: 0
- The type of path to calculate. One of:
* 0 --- Shortest
* 1 --- Fastest
* - **Vector layer with start points**
- ``START_POINTS``
- [vector: point]
- Point vector layer whose features are used as start
points of the routes
* - **End point (x, y)**
- ``END_POINT``
- [coordinates]
- Point feature representing the end point of the routes
* - **Shortest path**
- ``OUTPUT``
- [vector: line]
- Specify the output line layer for the shortest paths.
One of:
.. include:: ../algs_include.rst
:start-after: **layer_output_types**
:end-before: **end_layer_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. include:: ./networkanalysis.rst
:start-after: .. **network_advanced_parameters**
:end-before: .. **end_network_advanced_parameters**
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Shortest path**
- ``OUTPUT``
- [vector: line]
- Line layer of the shortest or fastest path
from each of the start points to the end point
Python code
...........
**Algorithm ID**: ``native:shortestpathlayertopoint``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _qgisshortestpathpointtolayer:
Shortest path (point to layer)
------------------------------
Computes the optimal (shortest or fastest) routes between a given
start point and multiple end points defined by a point vector layer.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Vector layer representing network**
- ``INPUT``
- [vector: line]
- Line vector layer representing the network to be covered
* - **Path type to calculate**
- ``STRATEGY``
- [enumeration]
Default: 0
- The type of path to calculate. One of:
* 0 --- Shortest
* 1 --- Fastest
* - **Start point (x, y)**
- ``START_POINT``
- [coordinates]
- Point feature representing the start point of the routes
* - **Vector layer with end points**
- ``END_POINTS``
- [vector: point]
- Point vector layer whose features are used as end
points of the routes
* - **Shortest path**
- ``OUTPUT``
- [vector: line]
- Specify the output line layer for the shortest paths.
One of:
.. include:: ../algs_include.rst
:start-after: **layer_output_types**
:end-before: **end_layer_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. include:: ./networkanalysis.rst
:start-after: .. **network_advanced_parameters**
:end-before: .. **end_network_advanced_parameters**
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Shortest path**
- ``OUTPUT``
- [vector: line]
- Line layer of the shortest or fastest path
from each of the start points to the end point
Python code
...........
**Algorithm ID**: ``native:shortestpathpointtolayer``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _qgisshortestpathpointtopoint:
Shortest path (point to point)
------------------------------
Computes the optimal (shortest or fastest) route between a given start
point and a given end point.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Vector layer representing network**
- ``INPUT``
- [vector: line]
- Line vector layer representing the network to be covered
* - **Path type to calculate**
- ``STRATEGY``
- [enumeration]
Default: 0
- The type of path to calculate. One of:
* 0 --- Shortest
* 1 --- Fastest
* - **Start point (x, y)**
- ``START_POINT``
- [coordinates]
- Point feature representing the start point of the routes
* - **End point (x, y)**
- ``END_POINT``
- [coordinates]
- Point feature representing the end point of the routes
* - **Shortest path**
- ``OUTPUT``
- [vector: line]
- Specify the output line layer for the shortest paths.
One of:
.. include:: ../algs_include.rst
:start-after: **layer_output_types**
:end-before: **end_layer_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. include:: ./networkanalysis.rst
:start-after: .. **network_advanced_parameters**
:end-before: .. **end_network_advanced_parameters**
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Shortest path**
- ``OUTPUT``
- [vector: line]
- Line layer of the shortest or fastest path
from each of the start point to the end point
Python code
...........
**Algorithm ID**: ``native:shortestpathpointtopoint``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**