Quantum pipeline using the Quantum Trainer

import warnings
warnings.filterwarnings("ignore")

import os
os.environ["TOKENIZERS_PARALLELISM"] = "false"

import numpy as np

BATCH_SIZE = 30
EPOCHS = 120
SEED = 2

Read in the data and create diagrams

def read_data(filename):
    labels, sentences = [], []
    with open(filename) as f:
        for line in f:
            t = int(line[0])
            labels.append([t, 1-t])
            sentences.append(line[1:].strip())
    return labels, sentences


train_labels, train_data = read_data('datasets/mc_train_data.txt')
dev_labels, dev_data = read_data('datasets/mc_dev_data.txt')
test_labels, test_data = read_data('datasets/mc_test_data.txt')

Create diagrams

from lambeq import BobcatParser

parser = BobcatParser(verbose='text')

raw_train_diagrams = parser.sentences2diagrams(train_data)
raw_dev_diagrams = parser.sentences2diagrams(dev_data)
raw_test_diagrams = parser.sentences2diagrams(test_data)

Tagging sentences.
Parsing tagged sentences.
Turning parse trees to diagrams.
Tagging sentences.
Parsing tagged sentences.
Turning parse trees to diagrams.
Tagging sentences.
Parsing tagged sentences.
Turning parse trees to diagrams.

Remove the cups

from lambeq import RemoveCupsRewriter

remove_cups = RemoveCupsRewriter()

train_diagrams = [remove_cups(diagram) for diagram in raw_train_diagrams]
dev_diagrams = [remove_cups(diagram) for diagram in raw_dev_diagrams]
test_diagrams = [remove_cups(diagram) for diagram in raw_test_diagrams]

train_diagrams[0].draw()

Create circuits

from lambeq import AtomicType, IQPAnsatz

ansatz = IQPAnsatz({AtomicType.NOUN: 1, AtomicType.SENTENCE: 1},
                   n_layers=1, n_single_qubit_params=3)

train_circuits = [ansatz(diagram) for diagram in train_diagrams]
dev_circuits =  [ansatz(diagram) for diagram in dev_diagrams]
test_circuits = [ansatz(diagram) for diagram in test_diagrams]

train_circuits[0].draw(figsize=(9, 9))

Parameterise

from pytket.extensions.qiskit import AerBackend
from lambeq import TketModel

all_circuits = train_circuits+dev_circuits+test_circuits

backend = AerBackend()
backend_config = {
    'backend': backend,
    'compilation': backend.default_compilation_pass(2),
    'shots': 8192
}
model = TketModel.from_diagrams(all_circuits, backend_config=backend_config)

Define evaluation metric

from lambeq import BinaryCrossEntropyLoss

# Using the builtin binary cross-entropy error from lambeq
bce = BinaryCrossEntropyLoss()

acc = lambda y_hat, y: np.sum(np.round(y_hat) == y) / len(y) / 2  # half due to double-counting

Initialize trainer

from lambeq import QuantumTrainer, SPSAOptimizer

trainer = QuantumTrainer(
    model,
    loss_function=bce,
    epochs=EPOCHS,
    optimizer=SPSAOptimizer,
    optim_hyperparams={'a': 0.05, 'c': 0.06, 'A':0.01*EPOCHS},
    evaluate_functions={'acc': acc},
    evaluate_on_train=True,
    verbose='text',
    seed=0
)

from lambeq import Dataset

train_dataset = Dataset(
            train_circuits,
            train_labels,
            batch_size=BATCH_SIZE)

val_dataset = Dataset(dev_circuits, dev_labels, shuffle=False)

Train

trainer.fit(train_dataset, val_dataset, log_interval=12)

Epoch 12:   train/loss: 2.1017   valid/loss: 0.8054   train/time: 2m21s   valid/time: 29.87s   train/acc: 0.5929   valid/acc: 0.5167
Epoch 24:   train/loss: 0.8344   valid/loss: 0.7573   train/time: 2m16s   valid/time: 30.83s   train/acc: 0.5786   valid/acc: 0.5500
Epoch 36:   train/loss: 1.8189   valid/loss: 0.9036   train/time: 2m17s   valid/time: 30.32s   train/acc: 0.5286   valid/acc: 0.4667
Epoch 48:   train/loss: 1.8901   valid/loss: 0.7692   train/time: 2m11s   valid/time: 28.47s   train/acc: 0.5857   valid/acc: 0.6500
Epoch 60:   train/loss: 0.5390   valid/loss: 0.4898   train/time: 2m16s   valid/time: 28.18s   train/acc: 0.7571   valid/acc: 0.7333
Epoch 72:   train/loss: 0.4840   valid/loss: 0.4777   train/time: 2m10s   valid/time: 28.43s   train/acc: 0.8000   valid/acc: 0.7333
Epoch 84:   train/loss: 0.3344   valid/loss: 0.4273   train/time: 2m14s   valid/time: 28.68s   train/acc: 0.8071   valid/acc: 0.8333
Epoch 96:   train/loss: 0.4518   valid/loss: 0.4237   train/time: 2m12s   valid/time: 29.25s   train/acc: 0.8286   valid/acc: 0.7667
Epoch 108:  train/loss: 0.3554   valid/loss: 0.4414   train/time: 2m12s   valid/time: 28.41s   train/acc: 0.8714   valid/acc: 0.7667
Epoch 120:  train/loss: 0.2696   valid/loss: 0.4609   train/time: 2m12s   valid/time: 28.06s   train/acc: 0.7857   valid/acc: 0.7333

Training completed!
train/time: 22m20s   train/time_per_epoch: 11.17s   train/time_per_step: 3.72s   valid/time: 4m50s   valid/time_per_eval: 2.42s

Show results

import matplotlib.pyplot as plt

fig, ((ax_tl, ax_tr), (ax_bl, ax_br)) = plt.subplots(2, 2, sharex=True, sharey='row', figsize=(10, 6))
ax_tl.set_title('Training set')
ax_tr.set_title('Development set')
ax_bl.set_xlabel('Iterations')
ax_br.set_xlabel('Iterations')
ax_bl.set_ylabel('Accuracy')
ax_tl.set_ylabel('Loss')

colours = iter(plt.rcParams['axes.prop_cycle'].by_key()['color'])
range_ = np.arange(1, trainer.epochs + 1)
ax_tl.plot(range_, trainer.train_epoch_costs, color=next(colours))
ax_bl.plot(range_, trainer.train_eval_results['acc'], color=next(colours))
ax_tr.plot(range_, trainer.val_costs, color=next(colours))
ax_br.plot(range_, trainer.val_eval_results['acc'], color=next(colours))

test_acc = acc(model(test_circuits), test_labels)
print('Test accuracy:', test_acc)

Test accuracy: 0.8166666666666667