Note
Click here to download the full example code or to run this example in your browser via Binder
Label Propagation digits active learning¶
Demonstrates an active learning technique to learn handwritten digits using label propagation.
We start by training a label propagation model with only 10 labeled points,
then we select the top five most uncertain points to label. Next, we train
with 15 labeled points (original 10 + 5 new ones). We repeat this process
four times to have a model trained with 30 labeled examples. Note you can
increase this to label more than 30 by changing max_iterations. Labeling
more than 30 can be useful to get a sense for the speed of convergence of
this active learning technique.
A plot will appear showing the top 5 most uncertain digits for each iteration of training. These may or may not contain mistakes, but we will train the next model with their true labels.
Iteration 0 ______________________________________________________________________
Label Spreading model: 40 labeled & 290 unlabeled (330 total)
precision recall f1-score support
0 1.00 1.00 1.00 22
1 0.78 0.69 0.73 26
2 0.93 0.93 0.93 29
3 1.00 0.89 0.94 27
4 0.92 0.96 0.94 23
5 0.96 0.70 0.81 33
6 0.97 0.97 0.97 35
7 0.94 0.91 0.92 33
8 0.62 0.89 0.74 28
9 0.73 0.79 0.76 34
accuracy 0.87 290
macro avg 0.89 0.87 0.87 290
weighted avg 0.88 0.87 0.87 290
Confusion matrix
[[22 0 0 0 0 0 0 0 0 0]
[ 0 18 2 0 0 0 1 0 5 0]
[ 0 0 27 0 0 0 0 0 2 0]
[ 0 0 0 24 0 0 0 0 3 0]
[ 0 1 0 0 22 0 0 0 0 0]
[ 0 0 0 0 0 23 0 0 0 10]
[ 0 1 0 0 0 0 34 0 0 0]
[ 0 0 0 0 0 0 0 30 3 0]
[ 0 3 0 0 0 0 0 0 25 0]
[ 0 0 0 0 2 1 0 2 2 27]]
Iteration 1 ______________________________________________________________________
Label Spreading model: 45 labeled & 285 unlabeled (330 total)
precision recall f1-score support
0 1.00 1.00 1.00 22
1 0.79 1.00 0.88 22
2 1.00 0.93 0.96 29
3 1.00 1.00 1.00 26
4 0.92 0.96 0.94 23
5 0.96 0.70 0.81 33
6 1.00 0.97 0.99 35
7 0.94 0.91 0.92 33
8 0.77 0.86 0.81 28
9 0.73 0.79 0.76 34
accuracy 0.90 285
macro avg 0.91 0.91 0.91 285
weighted avg 0.91 0.90 0.90 285
Confusion matrix
[[22 0 0 0 0 0 0 0 0 0]
[ 0 22 0 0 0 0 0 0 0 0]
[ 0 0 27 0 0 0 0 0 2 0]
[ 0 0 0 26 0 0 0 0 0 0]
[ 0 1 0 0 22 0 0 0 0 0]
[ 0 0 0 0 0 23 0 0 0 10]
[ 0 1 0 0 0 0 34 0 0 0]
[ 0 0 0 0 0 0 0 30 3 0]
[ 0 4 0 0 0 0 0 0 24 0]
[ 0 0 0 0 2 1 0 2 2 27]]
Iteration 2 ______________________________________________________________________
Label Spreading model: 50 labeled & 280 unlabeled (330 total)
precision recall f1-score support
0 1.00 1.00 1.00 22
1 0.85 1.00 0.92 22
2 1.00 1.00 1.00 28
3 1.00 1.00 1.00 26
4 0.87 1.00 0.93 20
5 0.96 0.70 0.81 33
6 1.00 0.97 0.99 35
7 0.94 1.00 0.97 32
8 0.92 0.86 0.89 28
9 0.73 0.79 0.76 34
accuracy 0.92 280
macro avg 0.93 0.93 0.93 280
weighted avg 0.93 0.92 0.92 280
Confusion matrix
[[22 0 0 0 0 0 0 0 0 0]
[ 0 22 0 0 0 0 0 0 0 0]
[ 0 0 28 0 0 0 0 0 0 0]
[ 0 0 0 26 0 0 0 0 0 0]
[ 0 0 0 0 20 0 0 0 0 0]
[ 0 0 0 0 0 23 0 0 0 10]
[ 0 1 0 0 0 0 34 0 0 0]
[ 0 0 0 0 0 0 0 32 0 0]
[ 0 3 0 0 1 0 0 0 24 0]
[ 0 0 0 0 2 1 0 2 2 27]]
Iteration 3 ______________________________________________________________________
Label Spreading model: 55 labeled & 275 unlabeled (330 total)
precision recall f1-score support
0 1.00 1.00 1.00 22
1 0.85 1.00 0.92 22
2 1.00 1.00 1.00 27
3 1.00 1.00 1.00 26
4 0.87 1.00 0.93 20
5 0.96 0.87 0.92 31
6 1.00 0.97 0.99 35
7 1.00 1.00 1.00 31
8 0.92 0.86 0.89 28
9 0.88 0.85 0.86 33
accuracy 0.95 275
macro avg 0.95 0.95 0.95 275
weighted avg 0.95 0.95 0.95 275
Confusion matrix
[[22 0 0 0 0 0 0 0 0 0]
[ 0 22 0 0 0 0 0 0 0 0]
[ 0 0 27 0 0 0 0 0 0 0]
[ 0 0 0 26 0 0 0 0 0 0]
[ 0 0 0 0 20 0 0 0 0 0]
[ 0 0 0 0 0 27 0 0 0 4]
[ 0 1 0 0 0 0 34 0 0 0]
[ 0 0 0 0 0 0 0 31 0 0]
[ 0 3 0 0 1 0 0 0 24 0]
[ 0 0 0 0 2 1 0 0 2 28]]
Iteration 4 ______________________________________________________________________
Label Spreading model: 60 labeled & 270 unlabeled (330 total)
precision recall f1-score support
0 1.00 1.00 1.00 22
1 0.96 1.00 0.98 22
2 1.00 0.96 0.98 27
3 0.96 1.00 0.98 25
4 0.86 1.00 0.93 19
5 0.96 0.87 0.92 31
6 1.00 0.97 0.99 35
7 1.00 1.00 1.00 31
8 0.92 0.96 0.94 25
9 0.88 0.85 0.86 33
accuracy 0.96 270
macro avg 0.95 0.96 0.96 270
weighted avg 0.96 0.96 0.96 270
Confusion matrix
[[22 0 0 0 0 0 0 0 0 0]
[ 0 22 0 0 0 0 0 0 0 0]
[ 0 0 26 1 0 0 0 0 0 0]
[ 0 0 0 25 0 0 0 0 0 0]
[ 0 0 0 0 19 0 0 0 0 0]
[ 0 0 0 0 0 27 0 0 0 4]
[ 0 1 0 0 0 0 34 0 0 0]
[ 0 0 0 0 0 0 0 31 0 0]
[ 0 0 0 0 1 0 0 0 24 0]
[ 0 0 0 0 2 1 0 0 2 28]]
# Authors: Clay Woolam <clay@woolam.org>
# License: BSD
import numpy as np
import matplotlib.pyplot as plt
from scipy import stats
from sklearn import datasets
from sklearn.semi_supervised import LabelSpreading
from sklearn.metrics import classification_report, confusion_matrix
digits = datasets.load_digits()
rng = np.random.RandomState(0)
indices = np.arange(len(digits.data))
rng.shuffle(indices)
X = digits.data[indices[:330]]
y = digits.target[indices[:330]]
images = digits.images[indices[:330]]
n_total_samples = len(y)
n_labeled_points = 40
max_iterations = 5
unlabeled_indices = np.arange(n_total_samples)[n_labeled_points:]
f = plt.figure()
for i in range(max_iterations):
if len(unlabeled_indices) == 0:
print("No unlabeled items left to label.")
break
y_train = np.copy(y)
y_train[unlabeled_indices] = -1
lp_model = LabelSpreading(gamma=0.25, max_iter=20)
lp_model.fit(X, y_train)
predicted_labels = lp_model.transduction_[unlabeled_indices]
true_labels = y[unlabeled_indices]
cm = confusion_matrix(true_labels, predicted_labels, labels=lp_model.classes_)
print("Iteration %i %s" % (i, 70 * "_"))
print(
"Label Spreading model: %d labeled & %d unlabeled (%d total)"
% (n_labeled_points, n_total_samples - n_labeled_points, n_total_samples)
)
print(classification_report(true_labels, predicted_labels))
print("Confusion matrix")
print(cm)
# compute the entropies of transduced label distributions
pred_entropies = stats.distributions.entropy(lp_model.label_distributions_.T)
# select up to 5 digit examples that the classifier is most uncertain about
uncertainty_index = np.argsort(pred_entropies)[::-1]
uncertainty_index = uncertainty_index[
np.in1d(uncertainty_index, unlabeled_indices)
][:5]
# keep track of indices that we get labels for
delete_indices = np.array([], dtype=int)
# for more than 5 iterations, visualize the gain only on the first 5
if i < 5:
f.text(
0.05,
(1 - (i + 1) * 0.183),
"model %d\n\nfit with\n%d labels" % ((i + 1), i * 5 + 10),
size=10,
)
for index, image_index in enumerate(uncertainty_index):
image = images[image_index]
# for more than 5 iterations, visualize the gain only on the first 5
if i < 5:
sub = f.add_subplot(5, 5, index + 1 + (5 * i))
sub.imshow(image, cmap=plt.cm.gray_r, interpolation="none")
sub.set_title(
"predict: %i\ntrue: %i"
% (lp_model.transduction_[image_index], y[image_index]),
size=10,
)
sub.axis("off")
# labeling 5 points, remote from labeled set
(delete_index,) = np.where(unlabeled_indices == image_index)
delete_indices = np.concatenate((delete_indices, delete_index))
unlabeled_indices = np.delete(unlabeled_indices, delete_indices)
n_labeled_points += len(uncertainty_index)
f.suptitle(
"Active learning with Label Propagation.\nRows show 5 most "
"uncertain labels to learn with the next model.",
y=1.15,
)
plt.subplots_adjust(left=0.2, bottom=0.03, right=0.9, top=0.9, wspace=0.2, hspace=0.85)
plt.show()
Total running time of the script: ( 0 minutes 0.512 seconds)
