CODEWITHSUNDEEP
drake
Liqian
Liqian

Reputation: 41

How to Determine the Type of Abstract Input Ports after a System Has Been Constructed?

I'm trying to automate the declaration of output ports in one system (System A) based on the input ports of another system (System B). My approach involves constructing System B first and then passing it into the __init__ function of System A.

For vector-valued ports, this process is straightforward since I can retrieve the size of the vector input ports of System B and declare corresponding vector output ports in System A accordingly. However, I'm struggling with abstract ports.

I attempted to create a default context for System B and then evaluate the abstract input ports using that context (absract_value = B.input_port.Eval(context)), hoping to infer the abstract value. However, since the ports haven't been connected yet, I encountered a runtime error.

Is there a method or workaround to determine the type (or structure) of abstract input ports in a Drake system without connecting or evaluating them? Any insights or suggestions would be greatly appreciated.

Upvotes: 0

Views: 68

Answers (1)

jwnimmer-tri
jwnimmer-tri

Reputation: 2449

Call pydrake.systems.framework.InputPort.Allocate as in system_b.get_input_port(i).Allocate() to create a sample value using the input port's type.

Upvotes: 1

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