Thanks for reporting this @riyasett . Would it be possible for you to share the code-snippet that produced this error so I can try to reproduce this on my end?

from grove.

from grove.

@riyasett I can't seem to find the notebook. Maybe github email filtered it out?

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Oh, I am extremely sorry. I sent you the notebook through email. I am attaching it here again.

I cannot attach the notebook (.ipynb) here...

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hmm .. I unfortunately still can't see the full code to reproduce the error. Can you turn the notebook into a small script that I can run? You can also copy-and-paste the code you are running into a comment here.

from grove.

import numpy as np
import pyquil.api as api
from pyquil.paulis import PauliTerm, PauliSum
import networkx as nx
from scipy.optimize import minimize
from grove.pyqaoa.qaoa import QAOA
CXN = api.SyncConnection()

def print_fun(x):
print(x)

def maxcut_qaoa(graph, steps=1, rand_seed=None, connection=None, samples=None,
initial_beta=None, initial_gamma=None, minimizer_kwargs=None,
vqe_option=None):

if not isinstance(graph, nx.Graph) and isinstance(graph, list):
    maxcut_graph = nx.Graph()
    for edge in graph:
        maxcut_graph.add_edge(*edge)
    graph = maxcut_graph.copy()

cost_operators = []
driver_operators = []
for i, j in graph.edges():
    cost_operators.append(PauliTerm("Z", i, 0.5)*PauliTerm("Z", j) + PauliTerm("I", 0, -0.5))
for i in graph.nodes():
    driver_operators.append(PauliSum([PauliTerm("X", i, -1.0)]))

if connection is None:
    connection = CXN

if minimizer_kwargs is None:
    minimizer_kwargs = {'method': 'Nelder-Mead',
                        'options': {'ftol': 1.0e-2, 'xtol': 1.0e-2,
                                    'disp': False}}
if vqe_option is None:
    vqe_option = {'disp': print_fun, 'return_all': True,
                  'samples': samples}

qaoa_inst = QAOA(connection, len(graph.nodes()), steps=steps, cost_ham=cost_operators,
                 ref_hamiltonian=driver_operators, store_basis=True,
                 rand_seed=rand_seed,
                 init_betas=initial_beta,
                 init_gammas=initial_gamma,
                 minimizer=minimize,
                 minimizer_kwargs=minimizer_kwargs,
                 vqe_options=vqe_option)

return qaoa_inst

Sample Run:

Cutting 0 - 1 - 2 graph!

inst = maxcut_qaoa([(0, 1), (1, 2)], steps=2, rand_seed=42, samples=None)
betas, gammas = inst.get_angles()
probs = inst.probabilities(np.hstack((betas, gammas)))
for state, prob in zip(inst.states, probs):
print(state, prob)

print("Most frequent bitstring from sampling")
most_freq_string, sampling_results = inst.get_string(
betas, gammas)
print(most_freq_string)

from grove.

Thanks @riyasett, this will help me in reproducing your error!

from grove.

from grove.

@riyasett we just pushed a fix to master for your problem #109. Thanks @jonathanward for this. We will have a release of Grove coming up soon that will contain this fix.

from grove.

from grove.

@riyasett You're welcome! We just pushed a new release of grove. v1.4.0 I hope your problem is fixed there. I'll close this ticket, but feel free to reopen if you encounter the issue again!

from grove.