.set_parameters+
BPR link performance function method
Description
This .set_parameters allows you to set the BPR function’s parameters for specific link segments in case the network wide, mode and/or link segment type parameters do not suffice.
It is highly recommended to configure BPR parameters based on the link segment type rather than setting them for individual links. It is best practice to - in that case - create a new link segment type instead to reverting to this approach.
Signature
.set_parameters(alpha, beta, link_segment_xml_id)
with
| Parameter | Type | Unit | Compulsory | Description |
|---|---|---|---|---|
alpha |
float |
None |
YES | Alpha parameter of BPR function |
beta |
float |
None |
YES | Beta parameter of BPR function |
link_segment_xml_id |
string |
None |
YES | Link segment (XML) id to relate parameter to |
Return type
None
Example 1
Set only network wide defaults
from planit import *
# prep
planit_instance = Planit()
planit_instance.project.set(TrafficAssignment.TRADITIONAL_STATIC)
# set physical cost to BPR link performance function
planit_instance.project.assignment.set(PhysicalCost.BPR)
# specifically set the alpha and beta for link segment with XML id of "3"
alpha = 0.87
beta = 5
planit_instance.project.assignment.physical_cost.set_parameters(alpha, beta, "3")
See also
N/A
Source code
Class BPRCostWrapper in projectwrappers.py