Index error when using binplot

[wahab2604]

When using pycalphad 0.9.1 and the binplot function I get an index error :

I have attached a tdb that causes the error, I'm using a associates model and this tdb contains a solid solution
I also have another tdb that produces the same error and that tdb contains a Liquid+Liquid gap

Both of these tdb were working in pycalphad 0.9.0
TDB file.zip

I also get the same error when using the espei mcmc when setting approximate_equilibrium: False, however when I set it to True (which I mostly use) the error does not occur and the mcmc runs.

[richardotis]

I can reproduce this error with the above database and the following code:

from pycalphad import Database, binplot, variables as v
import matplotlib.pyplot as plt
dbf = Database('A_S_corrected.tdb')

# Define the components
comps = ['A', 'Q']
# Get all possible phases programmatically
phases = dbf.phases.keys()

# Plot the phase diagram, if no axes are supplied, a new figure with axes will be created automatically
binplot(dbf, comps, phases, {v.N: 1, v.P:101325, v.T: (300, 1000, 10), v.X('Q'):(0, 1, 0.02)})

plt.show()

[richardotis]

The cause of this error is an index offset being computed based on the number of nonvacant components, instead of the number of nonvacant elements. In general these numbers are not the same, and for associate models they usually are not, which is why you encountered this issue. I have a fix ready, and I'm just going to take a little time to prepare a test before I push the PR.

[wahab2604]

Thank you very much for your help