Simple question: correct way to save traces?

Questions
23

Hi @OriolAbril, @AlexAndorra ,
Good day.
I saved my model and trace using to_netcdf.

In a new script or I called it my prediction script,
I import the saved.nc using from_netcdf and I wish to perform sample_posterior_predictive.
However, I encountered some errors.
Is model.posterior is equivalent to trace in this case?

from arviz import from_netcdf
model = from_netcdf(‘trace123.nc’)

trace = model.posterior

import pymc3 as pm
import numpy as np

data = np.random.randn(20)

with pm.Model() as abc_model:
mu = pm.Normal(‘mu’, 0, 1)
sigma = 1.
returns = pm.Normal(‘returns’, mu=mu, sd=sigma, observed=data)

step = pm.Metropolis()

with abc_model:
mu_sim = sample_posterior_predictive(trace, model=abc_model, samples=500)

But I get error of keyerror is 0.
May I know why?
Thank you very much