Problem: There's an issue with setting the values of h_snow or rho_snow after initialization because of a conflict with the shapes of internal variables in the snow components. In each case, set_value works, but a failure occurs on calling update; in particular, on line 467, in update_swe, in snow_base.py.
The shape conflict doesn't occur when setting h_swe or SM.
Import the Babel-wrapped SnowDegreeDay component and create an instance.
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from cmt.components import SnowDegreeDay
sno = SnowDegreeDay()
Initialize the component.
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sno.initialize('./input/snow_degree_day-1.cfg')
Get the model time step (which has been broadcast over the grid).
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time_step = sno.get_value('model__time_step').max()
print 'Time step = {} s'.format(time_step)
Assign a new value to the snowpack depth. (Note that if this step is omitted, the model will update successfully.)
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sno.set_value('snowpack__depth', 0.6) # [m]
Check the new snowpack depth.
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h_snow = sno.get_value('snowpack__depth')
print h_snow.shape
h_snow
Advance the model.
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sno.update(time_step)
Note: I believe I've identified the issue. TopoFlow uses Numpy arrays for all internal variables, including scalars. At some point (my hunch is in the Babelized set_value method), a one-element list, instead of a single scalar value, was set as data for these variables. This caused the shape mismatches. I fixed this problem by adding a check in the set_value method that we grafted onto TopoFlow:
if src.shape == (1,):
src = np.array(src[0])
This converts the one-element list into a scalar.
I think this fix is robust.
Finalize the component.
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sno.finalize()
Result: Problem solved, assuming my fix holds up.
For reference, here's the stack trace of the error that had been occurring:
An error occured inside a babel wrapper. Here is the traceback.
Traceback (most recent call last):
File "/home/csdms/wmt/topoflow.0/csdms/install/lib/python2.7/site-packages/csdms/SnowDegreeDay_Impl.py", line 696, in _wrap
return func(*args)
File "/home/csdms/wmt/topoflow.0/csdms/install/lib/python2.7/site-packages/csdms/SnowDegreeDay_Impl.py", line 107, in update
self._model.update_until(time_interval)
File "/home/csdms/wmt/topoflow.0/cache/topoflow-12d38ce246/topoflow/utils/BMI_base.py", line 1104, in update_until
self.update()
File "/home/csdms/wmt/topoflow.0/cache/topoflow-12d38ce246/topoflow/components/snow_base.py", line 238, in update
self.update_swe()
File "/home/csdms/wmt/topoflow.0/cache/topoflow-12d38ce246/topoflow/components/snow_base.py", line 467, in update_swe
self.h_swe -= dh2_swe
ValueError: non-broadcastable output operand with shape () doesn't match the broadcast shape (1,)