How to traverse into components of a model?

[lagamura]

Hi, i am trying to traverse in all the components which are of constant type, and get their value.

I was trying something like:

for component in model.components:
      value = model[component]
      ...

"but the components object is not iterable"

What is the proper way accessing the components?

[enekomartinmartinez]

Hi @lagamura,
model.components is a class that manages the components, that is why you cannot iterate over it.
I recommend you to use the model documentation to iterate over the components, it is a pandas.DataFrame, for example (teacup.mdl):

>>> model.doc
             Real Name              Py Name Subscripts                      Units          Limits       Type Subtype                                            Comment
0  Characteristic Time  characteristic_time       None                    Minutes      (0.0, nan)   Constant  Normal  How long will it take the teacup to cool 1/e o...
1           FINAL TIME           final_time       None                     Minute      (nan, nan)   Constant  Normal                 The final time for the simulation.
2    Heat Loss to Room    heat_loss_to_room       None  Degrees Fahrenheit/Minute      (nan, nan)  Auxiliary  Normal  This is the rate at which heat flows from the ...
3         INITIAL TIME         initial_time       None                     Minute      (nan, nan)   Constant  Normal               The initial time for the simulation.
4     Room Temperature     room_temperature       None         Degrees Fahrenheit  (-459.67, nan)   Constant  Normal  Put in a check to ensure the room temperature ...
5              SAVEPER              saveper       None                     Minute      (0.0, nan)  Auxiliary  Normal         The frequency with which output is stored.
6            TIME STEP            time_step       None                     Minute      (0.0, nan)   Constant  Normal                  The time step for the simulation.
7   Teacup Temperature   teacup_temperature       None         Degrees Fahrenheit   (32.0, 212.0)   Stateful   Integ  The model is only valid for the liquid phase o...
8                 Time                 time       None                       None      (nan, nan)       None    None                         Current time of the model.

>>> for component_name in model.doc["Real Name"]:
...     print(component_name, model[component_name])
... 
Characteristic Time 10
FINAL TIME 30
Heat Loss to Room 11.0
INITIAL TIME 0
Room Temperature 70
SAVEPER 0.125
TIME STEP 0.125
Teacup Temperature 180
Time 0

The previous example iterated over all the components. You can get only the constant variables using the Type column:

>>> constant_vars = model.doc["Real Name"][model.doc["Type"] == "Constant"]
>>> for component_name in constant_vars:
...     print(component_name, model[component_name])
... 
Characteristic Time 10
FINAL TIME 30
INITIAL TIME 0
Room Temperature 70
TIME STEP 0.125