02a training a quantum model on a real dataset

# This code is from the tutorial at:
# https://qiskit-community.github.io/qiskit-machine-learning/tutorials/02a_training_a_quantum_model_on_a_real_dataset.html

from sklearn.datasets import load_iris

iris_data = load_iris()

print(iris_data.DESCR)

.. _iris_dataset:

Iris plants dataset
--------------------

**Data Set Characteristics:**

:Number of Instances: 150 (50 in each of three classes)
:Number of Attributes: 4 numeric, predictive attributes and the class
:Attribute Information:
    - sepal length in cm
    - sepal width in cm
    - petal length in cm
    - petal width in cm
    - class:
            - Iris-Setosa
            - Iris-Versicolour
            - Iris-Virginica

:Summary Statistics:

============== ==== ==== ======= ===== ====================
                Min  Max   Mean    SD   Class Correlation
============== ==== ==== ======= ===== ====================
sepal length:   4.3  7.9   5.84   0.83    0.7826
sepal width:    2.0  4.4   3.05   0.43   -0.4194
petal length:   1.0  6.9   3.76   1.76    0.9490  (high!)
petal width:    0.1  2.5   1.20   0.76    0.9565  (high!)
============== ==== ==== ======= ===== ====================

:Missing Attribute Values: None
:Class Distribution: 33.3% for each of 3 classes.
:Creator: R.A. Fisher
:Donor: Michael Marshall (MARSHALL%PLU@io.arc.nasa.gov)
:Date: July, 1988

The famous Iris database, first used by Sir R.A. Fisher. The dataset is taken
from Fisher's paper. Note that it's the same as in R, but not as in the UCI
Machine Learning Repository, which has two wrong data points.

This is perhaps the best known database to be found in the
pattern recognition literature.  Fisher's paper is a classic in the field and
is referenced frequently to this day.  (See Duda & Hart, for example.)  The
data set contains 3 classes of 50 instances each, where each class refers to a
type of iris plant.  One class is linearly separable from the other 2; the
latter are NOT linearly separable from each other.

.. dropdown:: References

  - Fisher, R.A. "The use of multiple measurements in taxonomic problems"
    Annual Eugenics, 7, Part II, 179-188 (1936); also in "Contributions to
    Mathematical Statistics" (John Wiley, NY, 1950).
  - Duda, R.O., & Hart, P.E. (1973) Pattern Classification and Scene Analysis.
    (Q327.D83) John Wiley & Sons.  ISBN 0-471-22361-1.  See page 218.
  - Dasarathy, B.V. (1980) "Nosing Around the Neighborhood: A New System
    Structure and Classification Rule for Recognition in Partially Exposed
    Environments".  IEEE Transactions on Pattern Analysis and Machine
    Intelligence, Vol. PAMI-2, No. 1, 67-71.
  - Gates, G.W. (1972) "The Reduced Nearest Neighbor Rule".  IEEE Transactions
    on Information Theory, May 1972, 431-433.
  - See also: 1988 MLC Proceedings, 54-64.  Cheeseman et al"s AUTOCLASS II
    conceptual clustering system finds 3 classes in the data.
  - Many, many more ...

features = iris_data.data
labels = iris_data.target

from sklearn.preprocessing import MinMaxScaler

features = MinMaxScaler().fit_transform(features)

import pandas as pd
import seaborn as sns

df = pd.DataFrame(iris_data.data, columns=iris_data.feature_names)
df["class"] = pd.Series(iris_data.target)

sns.pairplot(df, hue="class", palette="tab10")

<seaborn.axisgrid.PairGrid at 0x1dc49420810>

from sklearn.model_selection import train_test_split
from qiskit_machine_learning.utils import algorithm_globals

algorithm_globals.random_seed = 123
train_features, test_features, train_labels, test_labels = train_test_split(
    features, labels, train_size=0.8, random_state=algorithm_globals.random_seed
)

from sklearn.svm import SVC

svc = SVC()
_ = svc.fit(train_features, train_labels)  # suppress printing the return value

train_score_c4 = svc.score(train_features, train_labels)
test_score_c4 = svc.score(test_features, test_labels)

print(f"Classical SVC on the training dataset: {train_score_c4:.2f}")
print(f"Classical SVC on the test dataset:     {test_score_c4:.2f}")

Classical SVC on the training dataset: 0.99
Classical SVC on the test dataset:     0.97

from qiskit.circuit.library import ZZFeatureMap

num_features = features.shape[1]

feature_map = ZZFeatureMap(feature_dimension=num_features, reps=1)
feature_map.decompose().draw(output="mpl", style="clifford", fold=20)

from qiskit.circuit.library import RealAmplitudes

ansatz = RealAmplitudes(num_qubits=num_features, reps=3)
ansatz.decompose().draw(output="mpl", style="clifford", fold=20)

from qiskit_machine_learning.optimizers import COBYLA, SPSA

optimizer = COBYLA(maxiter=100)

#from qiskit.primitives import Sampler
from quantumrings.toolkit.qiskit import QrSamplerV1 as Sampler

sampler = Sampler()

from matplotlib import pyplot as plt
from IPython.display import clear_output

objective_func_vals = []
plt.rcParams["figure.figsize"] = (12, 6)


def callback_graph(weights, obj_func_eval):
    clear_output(wait=True)
    objective_func_vals.append(obj_func_eval)
    plt.title("Objective function value against iteration")
    plt.xlabel("Iteration")
    plt.ylabel("Objective function value")
    plt.plot(range(len(objective_func_vals)), objective_func_vals)
    plt.show()

import time
from qiskit_machine_learning.algorithms.classifiers import VQC

vqc = VQC(
    sampler=sampler,
    feature_map=feature_map,
    ansatz=ansatz,
    optimizer=optimizer,
    callback=callback_graph,
)

# clear objective value history
objective_func_vals = []

start = time.time()
vqc.fit(train_features, train_labels)
elapsed = time.time() - start

print(f"Training time: {round(elapsed)} seconds")

Training time: 803 seconds

train_score_q4 = vqc.score(train_features, train_labels)
test_score_q4 = vqc.score(test_features, test_labels)

print(f"Quantum VQC on the training dataset: {train_score_q4:.2f}")
print(f"Quantum VQC on the test dataset:     {test_score_q4:.2f}")

Quantum VQC on the training dataset: 0.63
Quantum VQC on the test dataset:     0.53

from sklearn.decomposition import PCA

features = PCA(n_components=2).fit_transform(features)

plt.rcParams["figure.figsize"] = (6, 6)
sns.scatterplot(x=features[:, 0], y=features[:, 1], hue=labels, palette="tab10")

<Axes: >

train_features, test_features, train_labels, test_labels = train_test_split(
    features, labels, train_size=0.8, random_state=algorithm_globals.random_seed
)

svc.fit(train_features, train_labels)

train_score_c2 = svc.score(train_features, train_labels)
test_score_c2 = svc.score(test_features, test_labels)

print(f"Classical SVC on the training dataset: {train_score_c2:.2f}")
print(f"Classical SVC on the test dataset:     {test_score_c2:.2f}")

Classical SVC on the training dataset: 0.97
Classical SVC on the test dataset:     0.90

num_features = features.shape[1]

feature_map = ZZFeatureMap(feature_dimension=num_features, reps=1)
ansatz = RealAmplitudes(num_qubits=num_features, reps=3)

optimizer = COBYLA(maxiter=40)

vqc = VQC(
    sampler=sampler,
    feature_map=feature_map,
    ansatz=ansatz,
    optimizer=optimizer,
    callback=callback_graph,
)

# clear objective value history
objective_func_vals = []

# make the objective function plot look nicer.
plt.rcParams["figure.figsize"] = (12, 6)


start = time.time()
vqc.fit(train_features, train_labels)
elapsed = time.time() - start

print(f"Training time: {round(elapsed)} seconds")

Training time: 138 seconds

train_score_q2_ra = vqc.score(train_features, train_labels)
test_score_q2_ra = vqc.score(test_features, test_labels)

print(f"Quantum VQC on the training dataset using RealAmplitudes: {train_score_q2_ra:.2f}")
print(f"Quantum VQC on the test dataset using RealAmplitudes:     {test_score_q2_ra:.2f}")

Quantum VQC on the training dataset using RealAmplitudes: 0.53
Quantum VQC on the test dataset using RealAmplitudes:     0.43

from qiskit.circuit.library import EfficientSU2

ansatz = EfficientSU2(num_qubits=num_features, reps=3)
optimizer = COBYLA(maxiter=40)

vqc = VQC(
    sampler=sampler,
    feature_map=feature_map,
    ansatz=ansatz,
    optimizer=optimizer,
    callback=callback_graph,
)

# clear objective value history
objective_func_vals = []

start = time.time()
vqc.fit(train_features, train_labels)
elapsed = time.time() - start

print(f"Training time: {round(elapsed)} seconds")

Training time: 146 seconds

train_score_q2_eff = vqc.score(train_features, train_labels)
test_score_q2_eff = vqc.score(test_features, test_labels)

print(f"Quantum VQC on the training dataset using EfficientSU2: {train_score_q2_eff:.2f}")
print(f"Quantum VQC on the test dataset using EfficientSU2:     {test_score_q2_eff:.2f}")

Quantum VQC on the training dataset using EfficientSU2: 0.63
Quantum VQC on the test dataset using EfficientSU2:     0.63

print(f"Model                           | Test Score | Train Score")
print(f"SVC, 4 features                 | {train_score_c4:10.2f} | {test_score_c4:10.2f}")
print(f"VQC, 4 features, RealAmplitudes | {train_score_q4:10.2f} | {test_score_q4:10.2f}")
print(f"----------------------------------------------------------")
print(f"SVC, 2 features                 | {train_score_c2:10.2f} | {test_score_c2:10.2f}")
print(f"VQC, 2 features, RealAmplitudes | {train_score_q2_ra:10.2f} | {test_score_q2_ra:10.2f}")
print(f"VQC, 2 features, EfficientSU2   | {train_score_q2_eff:10.2f} | {test_score_q2_eff:10.2f}")

Model                           | Test Score | Train Score
SVC, 4 features                 |       0.99 |       0.97
VQC, 4 features, RealAmplitudes |       0.63 |       0.53
----------------------------------------------------------
SVC, 2 features                 |       0.97 |       0.90
VQC, 2 features, RealAmplitudes |       0.53 |       0.43
VQC, 2 features, EfficientSU2   |       0.63 |       0.63