I have just run the following snippet of code: mcmc_args=dict(parallel = True,niter=10) history = gt.mcmc_equilibrate(state, wait=1000, history=True,mcmc_args=mcmc_args) with open('history1.pkl','wb') as his1_pkl: pickle.dump(history,his1_pkl,-1) According to the manual history is a "list of tuples of the form (iteration, entropy)". When unpickling it however I get a list of length 2000. Each element in the list is another list of length two containing `nan` as first entry and then a single-digit integer as second entry. A couple of questions: 1) I would expect a tuple, not a list for each entry in the list. Is the manual wrong or is the code wrong? Or did I do something wrong? 2) Why am I receiving `nan` rather than a value for "iteration" as first entry of my list? 3) Is there a particular reason why the length of the list is precisely 2000 in this case? (Obviously there is, I just haven't quite figured it out yet.) Best, Philipp -- View this message in context: http://main-discussion-list-for-the-graph-tool-project.982480.n3.nabble.com/... Sent from the Main discussion list for the graph-tool project mailing list archive at Nabble.com.