How did you generate idata (i.e., what arguments did you pass to pm.sample())? And what version of pymc are you using? It looks like you are assuming a (v4-style) inferenceData object, but idata is instead a (v3-style) MultiTrace object.
How did you generate idata (i.e., what arguments did you pass to pm.sample())? And what version of pymc are you using? It looks like you are assuming a (v4-style) inferenceData object, but idata is instead a (v3-style) MultiTrace object.