23.1.8. Network analysis¶

Service area (from layer)
Service area (from point)
Shortest path (layer to point)
Shortest path (point to layer)
Shortest path (point to point)

23.1.8.1. 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).

23.1.8.1.1. Parameters¶

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 seconds) for the Fastest path.

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

Optional

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)

Optional

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

Optional

TOLERANCE

[number]

Default: 0.0

Two lines with nodes closer than the specified tolerance are considered connected

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.

Service area (lines)

OUTPUT_LINES

[vector: line]

Default: [Create temporary layer]

Specify the output line layer for the service area. One of:

Skip output
Create Temporary Layer (TEMPORARY_OUTPUT)
Save to File…
Save to Geopackage…
Save to PostGIS Table…

The file encoding can also be changed here.

Service area (boundary nodes)

OUTPUT

[vector: point]

Default: [Skip output]

Specify the output point layer for the service area boundary nodes. One of:

Skip output
Create Temporary Layer (TEMPORARY_OUTPUT)
Save to File…
Save to Geopackage…
Save to PostGIS Table…

The file encoding can also be changed here.

23.1.8.1.2. Outputs¶

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.

23.1.8.1.3. Python code¶

Algorithm ID: qgis:serviceareafromlayer

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.8.2. 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).

23.1.8.2.1. Parameters¶

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	`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 seconds) for the Fastest path.
Advanced parameters	GUI only		Group of advanced network analysis parameters - see below.
Service area (lines)	`OUTPUT_LINES`	[vector: line] Default: `[Create temporary layer]`	Specify the output line layer for the service area. One of: Skip output Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to PostGIS Table… The file encoding can also be changed here.
Service area (boundary nodes)	`OUTPUT`	[vector: point] Default: `[Skip output]`	Specify the output point layer for the service area boundary nodes. One of: Skip output Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to PostGIS Table… The file encoding can also be changed here.

23.1.8.2.2. Advanced parameters¶

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 Optional	`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) Optional	`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 Optional	`TOLERANCE`	[number] Default: 0.0	Two lines with nodes closer than the specified tolerance are considered connected
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.

23.1.8.2.3. Outputs¶

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.

23.1.8.2.4. Python code¶

Algorithm ID: qgis:serviceareafrompoint

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.8.3. 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.

23.1.8.3.1. Parameters¶

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
Advanced parameters	GUI only		The Advanced parameters group:
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 Optional	`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) Optional	`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 Optional	`TOLERANCE`	[number] Default: 0.0	Two lines with nodes closer than the specified tolerance are considered connected
			End of the Advanced parameters group
Shortest path	`OUTPUT`	[vector: line]	Specify the output line layer for the shortest paths. One of: Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to PostGIS Table… The file encoding can also be changed here.

23.1.8.3.2. Outputs¶

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

23.1.8.3.3. Python code¶

Algorithm ID: qgis:shortestpathlayertopoint

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.8.4. 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.

23.1.8.4.1. Parameters¶

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
Direction field Optional Advanced	`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 Advanced	`VALUE_FORWARD`	[string] Default: ‘’ (empty string)	Value set in the direction field to identify edges with a forward direction
Value for backward direction Optional Advanced	`VALUE_BACKWARD`	[string] Default: ‘’ (empty string)	Value set in the direction field to identify edges with a backward direction
Value for both directions Optional Advanced	`VALUE_BOTH`	[string] Default: ‘’ (empty string)	Value set in the direction field to identify bidirectional edges
Default direction Optional Advanced	`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 Advanced	`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) Optional Advanced	`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 Optional Advanced	`TOLERANCE`	[number] Default: 0.0	Two lines with nodes closer than the specified tolerance are considered connected
Shortest path	`OUTPUT`	[vector: line]	Specify the output line layer for the shortest paths. One of: Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to PostGIS Table… The file encoding can also be changed here.

23.1.8.4.2. Outputs¶

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

23.1.8.4.3. Python code¶

Algorithm ID: qgis:shortestpathpointtolayer

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.8.5. Shortest path (point to point)¶

Computes the optimal (shortest or fastest) route between a given start point and a given end point.

23.1.8.5.1. Parameters¶

Label	Name	Advanced	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
Direction field Optional	`DIRECTION_FIELD`	X	[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`	X	[string] Default: ‘’ (empty string)	Value set in the direction field to identify edges with a forward direction
Value for backward direction Optional	`VALUE_BACKWARD`	X	[string] Default: ‘’ (empty string)	Value set in the direction field to identify edges with a backward direction
Value for both directions Optional	`VALUE_BOTH`	X	[string] Default: ‘’ (empty string)	Value set in the direction field to identify bidirectional edges
Default direction Optional	`DEFAULT_DIRECTION`	X	[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`	X	[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) Optional	`DEFAULT_SPEED`	X	[number] Default: 50.0	Value to use to calculate the travel time if no speed field is provided for an edge
Topology tolerance Optional	`TOLERANCE`	X	[number] Default: 0.0	Two lines with nodes closer than the specified tolerance are considered connected
Shortest path	`OUTPUT`		[vector: line]	Specify the output line layer for the shortest paths. One of: Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to PostGIS Table… The file encoding can also be changed here.

23.1.8.5.2. Outputs¶

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

23.1.8.5.3. Python code¶

Algorithm ID: qgis:shortestpathpointtopoint

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.