24.1.13. Network analysis
24.1.13.1. Extract network end points
Extracts the end points (nodes) from a network line layer. Two definitions are available for identifying end points:
Nodes with only all incoming or all outgoing edges: Identifies ‘Source’ or ‘Sink’ nodes based on the direction of flow. These are nodes where flow can start (only outgoing) or stop (only incoming).
Nodes connected to a single edge: Identifies topological ‘dead-ends’ or ‘dangles’, regardless of directionality. This checks if the node is connected to only one other distinct node.
Parameters
Basic parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Vector layer representing network |
|
[vector: line] |
Line vector layer representing the network to extract end points from. |
End point definition |
|
[enumeration] Default: 1 |
The definition used to identify end points. One of:
|
Network endpoints |
|
[vector: point] Default: |
Specify the output point layer for the extracted network end points. One of:
The file encoding can also be changed here. |
Advanced parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Direction field Optional |
|
[tablefield: any] |
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 Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a forward direction |
Value for backward direction Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a backward direction |
Value for both directions Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify bidirectional edges |
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:
|
Topology tolerance |
|
[numeric: double] Default: 0.0 |
Two lines with nodes closer than the specified tolerance are considered connected |
Outputs
Label |
Name |
Type |
Description |
|---|---|---|---|
Network endpoints |
|
[vector: point] |
The output point layer for the extracted network end points. |
Python code
Algorithm ID: native:extractnetworkendpoints
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.
24.1.13.2. 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).
Note
This algorithm uses ellipsoid based measurements and respects the current ellipsoid settings.
Parameters
Basic parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Vector layer representing network |
|
[vector: line] |
Line vector layer representing the network to be covered |
Vector layer with start points |
|
[vector: point] |
Point vector layer whose features are used as start points to generate the service areas |
Path type to calculate |
|
[enumeration] Default: 0 |
The type of path to calculate. One of:
|
Travel cost (distance for “Shortest”, time for “Fastest”) |
|
[numeric: double] Default: 0.0 |
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) |
|
[vector: line] Default: |
Specify the output line layer for the service area. One of:
The file encoding can also be changed here. |
Service area (boundary nodes) |
|
[vector: point] Default: |
Specify the output point layer for the service area boundary nodes. One of:
The file encoding can also be changed here. |
Non-routable features |
|
[vector: point] Default: |
Specify the output which will be used to store any input features which could not be routed (e.g., those which are too far from the network layer). One of:
The file encoding can also be changed here. |
Advanced parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Direction field Optional |
|
[tablefield: any] |
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 Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a forward direction |
Value for backward direction Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a backward direction |
Value for both directions Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify bidirectional edges |
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:
|
Speed field Optional |
|
[tablefield: numeric] |
Field providing the speed value (in 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 (km/h) |
|
[numeric: double] Default: 50.0 |
Value to use to calculate the travel time if no speed value is provided for an edge in the specified field |
Topology tolerance |
|
[numeric: double] Default: 0.0 |
Two lines with nodes closer than the specified tolerance are considered connected |
Include upper/lower bound points |
|
[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. |
Maximum point distance from network Optional |
|
[numeric: double] Default: Not set |
Specifies an optional limit on the distance from the points to the network layer. If a point is further from the network than this distance it will be treated as non-routable. If not set, endpoints will be snapped to the nearest point on the network layer, regardless of how far away from the network they actually are. |
Outputs
Label |
Name |
Type |
Description |
|---|---|---|---|
Service area (boundary nodes) |
|
[vector: point] |
The output point layer with the service area boundary nodes. |
Service area (lines) |
|
[vector: line] |
Line layer representing the parts of the network that can be serviced by the start points, for the given cost. |
Non routable features |
|
[vector: point] |
An optional output which will be used to store any input features which could not be routed (e.g., those which are too far from the network layer). |
Python code
Algorithm ID: native: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.
24.1.13.3. 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).
Note
This algorithm uses ellipsoid based measurements and respects the current ellipsoid settings.
Parameters
Basic parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Vector layer representing the network |
|
[vector: line] |
Line vector layer representing the network to be covered |
Path type to calculate |
|
[enumeration] Default: 0 |
The type of path to calculate. One of:
|
Start point |
|
[coordinates] |
Coordinate of the point to calculate the service area around. Press the … button next to the option and click on the canvas to fill the parameter with the clicked point coordinate. |
Travel cost (distance for “Shortest”, time for “Fastest”) |
|
[numeric: double] Default: 0.0 |
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) Optional |
|
[vector: line] Default: |
Specify the output line layer for the service area. One of:
The file encoding can also be changed here. |
Service area (boundary nodes) Optional |
|
[vector: point] Default: |
Specify the output point layer for the service area boundary nodes. One of:
The file encoding can also be changed here. |
Advanced parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Direction field Optional |
|
[tablefield: any] |
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 Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a forward direction |
Value for backward direction Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a backward direction |
Value for both directions Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify bidirectional edges |
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:
|
Speed field Optional |
|
[tablefield: numeric] |
Field providing the speed value (in 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 (km/h) |
|
[numeric: double] Default: 50.0 |
Value to use to calculate the travel time if no speed value is provided for an edge in the specified field |
Topology tolerance |
|
[numeric: double] Default: 0.0 |
Two lines with nodes closer than the specified tolerance are considered connected |
Maximum point distance from network Optional |
|
[numeric: double] Default: 0.0 |
Specifies an optional limit on the distance from the start point to the network layer. If the point is further from the network than this distance an error will be raised. If not set, the point will be snapped to the nearest point on the network layer, regardless of how far away from the network it actually is. |
Include upper/lower bound points |
|
[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
Label |
Name |
Type |
Description |
|---|---|---|---|
Service area (boundary nodes) |
|
[vector: point] |
The output point layer with the service area boundary nodes. |
Service area (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
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.
24.1.13.4. 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.
Note
This algorithm uses ellipsoid based measurements and respects the current ellipsoid settings.
Parameters
Basic parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Vector layer representing network |
|
[vector: line] |
Line vector layer representing the network to be covered |
Path type to calculate |
|
[enumeration] Default: 0 |
The type of path to calculate. One of:
|
Vector layer with start points |
|
[vector: point] |
Point vector layer whose features are used as start points of the routes |
End point (x, y) |
|
[coordinates] |
Point feature representing the end point of the routes Press the … button next to the option and click on the canvas to fill the parameter with the clicked point coordinate. |
Shortest path |
|
[vector: line] Default: |
Specify the output line layer for the shortest paths. One of:
The file encoding can also be changed here. |
Non-routable features Optional |
|
[vector: point] Default: |
Specify the output which will be used to store any input features which could not be routed (e.g., those which are too far from the network layer). One of:
The file encoding can also be changed here. |
Advanced parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Direction field Optional |
|
[tablefield: any] |
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 Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a forward direction |
Value for backward direction Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a backward direction |
Value for both directions Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify bidirectional edges |
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:
|
Speed field Optional |
|
[tablefield: numeric] |
Field providing the speed value (in 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 (km/h) |
|
[numeric: double] Default: 50.0 |
Value to use to calculate the travel time if no speed value is provided for an edge in the specified field |
Topology tolerance |
|
[numeric: double] Default: 0.0 |
Two lines with nodes closer than the specified tolerance are considered connected |
Maximum point distance from network Optional |
|
[numeric: double] Default: Not set |
Specifies an optional limit on the distance from the start and end points to the network layer. If a start feature is further from the network than this distance it will be treated as non-routable. If the end point is further from the network than this distance an error will be raised. If not set, points will be snapped to the nearest point on the network layer, regardless of how far away from the network they actually are. |
Outputs
Label |
Name |
Type |
Description |
|---|---|---|---|
Shortest path |
|
[vector: line] |
Line layer of the shortest or fastest path from each of the start points to the end point |
Non routable features |
|
[vector: point] |
An optional output layer which will be used to store any input features which could not be routed (e.g., those which are too far from the network layer). |
Python code
Algorithm ID: native: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.
24.1.13.5. 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.
Note
This algorithm uses ellipsoid based measurements and respects the current ellipsoid settings.
Warning
This algorithm drops existing primary keys or FID values and regenerates them in output layers.
Parameters
Basic parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Vector layer representing network |
|
[vector: line] |
Line vector layer representing the network to be covered |
Path type to calculate |
|
[enumeration] Default: 0 |
The type of path to calculate. One of:
|
Start point |
|
[coordinates] |
Point feature representing the start point of the routes Press the … button next to the option and click on the canvas to fill the parameter with the clicked point coordinate. |
Vector layer with end points |
|
[vector: point] |
Point vector layer whose features are used as end points of the routes |
Shortest path |
|
[vector: line] Default: |
Specify the output line layer for the shortest paths. One of:
The file encoding can also be changed here. |
Non-routable features |
Optional |
[vector: point] Default: |
Specify the output which will be used to store any input features which could not be routed (e.g., those which are too far from the network layer). One of:
The file encoding can also be changed here. |
Advanced parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Direction field Optional |
|
[tablefield: any] |
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 Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a forward direction |
Value for backward direction Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a backward direction |
Value for both directions Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify bidirectional edges |
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:
|
Speed field Optional |
|
[tablefield: numeric] |
Field providing the speed value (in 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 (km/h) |
|
[numeric: double] Default: 50.0 |
Value to use to calculate the travel time if no speed value is provided for an edge in the specified field |
Topology tolerance |
|
[numeric: double] Default: 0.0 |
Two lines with nodes closer than the specified tolerance are considered connected |
Maximum point distance from network Optional |
|
[numeric: double] Default: Not set |
Specifies an optional limit on the distance from the start and end points to the network layer. If the start point is further from the network than this distance an error will be raised. If an end feature is further from the network than this distance it will be treated as non-routable. If not set, points will be snapped to the nearest point on the network layer, regardless of how far away from the network they actually are. |
Outputs
Label |
Name |
Type |
Description |
|---|---|---|---|
Shortest path |
|
[vector: line] |
Line layer of the shortest or fastest path from each of the start points to the end point |
Non routable features |
|
[vector: point] |
An optional output layer which will be used to store any input features which could not be routed (e.g., those which are too far from the network layer). |
Python code
Algorithm ID: native: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.
24.1.13.6. Shortest path (point to point)
Computes the optimal (shortest or fastest) route between a given start point and a given end point.
Note
This algorithm uses ellipsoid based measurements and respects the current ellipsoid settings.
Parameters
Basic parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Vector layer representing network |
|
[vector: line] |
Line vector layer representing the network to be covered |
Path type to calculate |
|
[enumeration] Default: 0 |
The type of path to calculate. One of:
|
Start point (x, y) |
|
[coordinates] |
Point feature representing the start point of the routes. Press the … button next to the option and click on the canvas to fill the parameter with the clicked point coordinate. |
End point (x, y) |
|
[coordinates] |
Point feature representing the end point of the routes. Press the … button next to the option and click on the canvas to fill the parameter with the clicked point coordinate. |
Shortest path |
|
[vector: line] |
Specify the output line layer for the shortest paths. One of:
The file encoding can also be changed here. |
Advanced parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Direction field Optional |
|
[tablefield: any] |
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 Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a forward direction |
Value for backward direction Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a backward direction |
Value for both directions Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify bidirectional edges |
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:
|
Speed field Optional |
|
[tablefield: numeric] |
Field providing the speed value (in 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 (km/h) |
|
[numeric: double] Default: 50.0 |
Value to use to calculate the travel time if no speed value is provided for an edge in the specified field |
Topology tolerance |
|
[numeric: double] Default: 0.0 |
Two lines with nodes closer than the specified tolerance are considered connected |
Maximum point distance from network Optional |
|
[numeric: double] Default: Not set |
Specifies an optional limit on the distance from the start and end points to the network layer. If either point is further from the network than this distance an error will be raised. If not set, points will be snapped to the nearest point on the network layer, regardless of how far away from the network they actually are. |
Outputs
Label |
Name |
Type |
Description |
|---|---|---|---|
Shortest path |
|
[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
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.
24.1.13.7. Validate network
Analyzes a network vector layer to identify data and topology errors that may affect network analysis tools (like shortest path). Optional checks include:
Validating the ‘Direction’ field to ensure all direction field values in the input layer match the configured forward/backward/both values. Errors will be reported if the direction field value is non-null and does not match one of the configured values.
Checking node-to-node separation. This check identifies nodes from the network graph that are closer to other nodes than the specified tolerance distance. This often indicates missed snaps or short segments in the input layer. In the case that a node violates this condition with multiple other nodes, only the closest violation will be reported.
Checking node-to-segment separation: This check identifies nodes that are closer to a line segment (e.g. a graph edge) than the specified tolerance distance, without being connected to it. In the case that a node violates this condition with multiple other edges, only the closest violation will be reported.
Two layers are output by this algorithm:
An output containing features from the original network layer which failed the direction validation checks.
An output representing the problematic node locations with a ‘error’ field explaining the error. This is a line layer, where the output features join the problematic node to the node or segment which failed the tolerance checks.
Parameters
Basic parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Vector layer representing network |
|
[vector: line] |
Line vector layer representing the network to be validated. |
Minimum separation between nodes Optional |
|
[numeric: double] Default: Not set |
The minimum allowed distance between two distint graph nodes. Nodes closer than this distance (but not identical) will be flagged as errors. Leave empty to disable this check. |
Minimum separation between nodes and non-noded segments Optional |
|
[numeric: double] Default: Not set |
The minimum allowed distance between a graph node and a graph edge (segment) that is not connected to the node. Nodes closer to a segment than this distance will be flagged. Leave empty to disable this check. |
Direction field Optional |
|
[tablefield: any] |
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 Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a forward direction |
Value for backward direction Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify edges with a backward direction |
Value for both directions Optional |
|
[string] Default: ‘’ (empty string) |
Value set in the direction field to identify bidirectional edges |
Invalid network features Optional |
|
[vector: line] Default: |
Specify the output line layer for the invalid network features. One of:
The file encoding can also be changed here. |
Invalid network nodes Optional |
|
[vector: line] Default: |
Specify the output line layer for the invalid network nodes. One of:
The file encoding can also be changed here. |
Advanced parameters
Label |
Name |
Type |
Description |
|---|---|---|---|
Topology tolerance |
|
[numeric: double] Default: 0.0 |
Two lines with nodes closer than the specified tolerance are considered connected |
Outputs
Label |
Name |
Type |
Description |
|---|---|---|---|
Invalid network features |
|
[vector: line] |
An output containing features from the original network layer which failed the direction validation checks. |
Invalid network nodes |
|
[vector: line] |
An output representing the problematic node locations with a ‘error’ field explaining the error. |
Python code
Algorithm ID: native:validatenetwork
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.