keras/keras_core/metrics/iou_metrics.py

748 lines
26 KiB
Python
Raw Normal View History

from keras_core import backend
from keras_core import initializers
from keras_core import operations as ops
from keras_core.api_export import keras_core_export
from keras_core.metrics.metric import Metric
from keras_core.metrics.metrics_utils import confusion_matrix
class _IoUBase(Metric):
"""Computes the confusion matrix for Intersection-Over-Union metrics.
Formula:
```python
iou = true_positives / (true_positives + false_positives + false_negatives)
```
Intersection-Over-Union is a common evaluation metric for semantic image
segmentation.
From IoUs of individual classes, the MeanIoU can be computed as the mean of
the individual IoUs.
To compute IoUs, the predictions are accumulated in a confusion matrix,
weighted by `sample_weight` and the metric is then calculated from it.
If `sample_weight` is `None`, weights default to 1.
Use `sample_weight` of 0 to mask values.
Args:
num_classes: The possible number of labels the prediction task can have.
name: (Optional) string name of the metric instance.
dtype: (Optional) data type of the metric result.
ignore_class: Optional integer. The ID of a class to be ignored during
metric computation. This is useful, for example, in segmentation
problems featuring a "void" class (commonly -1 or 255) in
segmentation maps. By default (`ignore_class=None`), all classes are
considered.
sparse_y_true: Whether labels are encoded using integers or
dense floating point vectors. If `False`, the `argmax` function
is used to determine each sample's most likely associated label.
sparse_y_pred: Whether predictions are encoded using integers or
dense floating point vectors. If `False`, the `argmax` function
is used to determine each sample's most likely associated label.
axis: (Optional) -1 is the dimension containing the logits.
Defaults to `-1`.
"""
def __init__(
self,
num_classes,
name=None,
dtype=None,
ignore_class=None,
sparse_y_true=True,
sparse_y_pred=True,
axis=-1,
):
# defaulting to float32 to avoid issues with confusion matrix
super().__init__(name=name, dtype=dtype or "float32")
self.num_classes = num_classes
self.ignore_class = ignore_class
self.sparse_y_true = sparse_y_true
self.sparse_y_pred = sparse_y_pred
self.axis = axis
self.total_cm = self.add_variable(
name="total_confusion_matrix",
shape=(num_classes, num_classes),
initializer=initializers.Zeros(),
)
def update_state(self, y_true, y_pred, sample_weight=None):
"""Accumulates the confusion matrix statistics.
Args:
y_true: The ground truth values.
y_pred: The predicted values.
sample_weight: Optional weighting of each example. Can
be a `Tensor` whose rank is either 0, or the same as `y_true`,
and must be broadcastable to `y_true`. Defaults to `1`.
Returns:
Update op.
"""
if not self.sparse_y_true:
y_true = ops.argmax(y_true, axis=self.axis)
if not self.sparse_y_pred:
y_pred = ops.argmax(y_pred, axis=self.axis)
y_true = ops.convert_to_tensor(y_true, dtype=self.dtype)
y_pred = ops.convert_to_tensor(y_pred, dtype=self.dtype)
# Flatten the input if its rank > 1.
if len(y_pred.shape) > 1:
y_pred = ops.reshape(y_pred, [-1])
if len(y_true.shape) > 1:
y_true = ops.reshape(y_true, [-1])
if sample_weight is None:
sample_weight = 1
sample_weight = ops.convert_to_tensor(sample_weight, dtype=self.dtype)
if len(sample_weight.shape) > 1:
sample_weight = ops.reshape(sample_weight, [-1])
sample_weight = ops.broadcast_to(sample_weight, y_true.shape)
if self.ignore_class is not None:
ignore_class = ops.convert_to_tensor(
self.ignore_class, y_true.dtype
)
valid_mask = ops.not_equal(y_true, ignore_class)
y_true = y_true[valid_mask]
y_pred = y_pred[valid_mask]
if sample_weight is not None:
sample_weight = sample_weight[valid_mask]
y_pred = ops.cast(y_pred, dtype=self.dtype)
y_true = ops.cast(y_true, dtype=self.dtype)
sample_weight = ops.cast(sample_weight, dtype=self.dtype)
current_cm = confusion_matrix(
y_true,
y_pred,
self.num_classes,
weights=sample_weight,
dtype="float32",
)
return self.total_cm.assign(self.total_cm + current_cm)
def reset_state(self):
self.total_cm.assign(
ops.zeros(self.total_cm.shape, dtype=self.total_cm.dtype)
)
@keras_core_export("keras_core.metrics.IoU")
class IoU(_IoUBase):
"""Computes the Intersection-Over-Union metric for specific target classes.
Formula:
```python
iou = true_positives / (true_positives + false_positives + false_negatives)
```
Intersection-Over-Union is a common evaluation metric for semantic image
segmentation.
To compute IoUs, the predictions are accumulated in a confusion matrix,
weighted by `sample_weight` and the metric is then calculated from it.
If `sample_weight` is `None`, weights default to 1.
Use `sample_weight` of 0 to mask values.
Note, this class first computes IoUs for all individual classes, then
returns the mean of IoUs for the classes that are specified by
`target_class_ids`. If `target_class_ids` has only one id value, the IoU of
that specific class is returned.
Args:
num_classes: The possible number of labels the prediction task can have.
target_class_ids: A tuple or list of target class ids for which the
metric is returned. To compute IoU for a specific class, a list
(or tuple) of a single id value should be provided.
name: (Optional) string name of the metric instance.
dtype: (Optional) data type of the metric result.
ignore_class: Optional integer. The ID of a class to be ignored during
metric computation. This is useful, for example, in segmentation
problems featuring a "void" class (commonly -1 or 255) in
segmentation maps. By default (`ignore_class=None`), all classes are
considered.
sparse_y_true: Whether labels are encoded using integers or
dense floating point vectors. If `False`, the `argmax` function
is used to determine each sample's most likely associated label.
sparse_y_pred: Whether predictions are encoded using integers or
dense floating point vectors. If `False`, the `argmax` function
is used to determine each sample's most likely associated label.
axis: (Optional) -1 is the dimension containing the logits.
Defaults to `-1`.
Examples:
Standalone usage:
>>> # cm = [[1, 1],
>>> # [1, 1]]
>>> # sum_row = [2, 2], sum_col = [2, 2], true_positives = [1, 1]
>>> # iou = true_positives / (sum_row + sum_col - true_positives))
>>> # iou = [0.33, 0.33]
>>> m = keras_core.metrics.IoU(num_classes=2, target_class_ids=[0])
>>> m.update_state([0, 0, 1, 1], [0, 1, 0, 1])
>>> m.result()
0.33333334
>>> m.reset_state()
>>> m.update_state([0, 0, 1, 1], [0, 1, 0, 1],
... sample_weight=[0.3, 0.3, 0.3, 0.1])
>>> # cm = [[0.3, 0.3],
>>> # [0.3, 0.1]]
>>> # sum_row = [0.6, 0.4], sum_col = [0.6, 0.4],
>>> # true_positives = [0.3, 0.1]
>>> # iou = [0.33, 0.14]
>>> m.result()
0.33333334
Usage with `compile()` API:
```python
model.compile(
optimizer='sgd',
loss='mse',
metrics=[keras_core.metrics.IoU(num_classes=2, target_class_ids=[0])])
```
"""
def __init__(
self,
num_classes,
target_class_ids,
name=None,
dtype=None,
ignore_class=None,
sparse_y_true=True,
sparse_y_pred=True,
axis=-1,
):
super().__init__(
name=name,
num_classes=num_classes,
ignore_class=ignore_class,
sparse_y_true=sparse_y_true,
sparse_y_pred=sparse_y_pred,
axis=axis,
dtype=dtype,
)
if max(target_class_ids) >= num_classes:
raise ValueError(
f"Target class id {max(target_class_ids)} "
"is out of range, which is "
f"[{0}, {num_classes})."
)
self.target_class_ids = list(target_class_ids)
def result(self):
"""Compute the intersection-over-union via the confusion matrix."""
sum_over_row = ops.cast(
ops.sum(self.total_cm, axis=0), dtype=self.dtype
)
sum_over_col = ops.cast(
ops.sum(self.total_cm, axis=1), dtype=self.dtype
)
true_positives = ops.cast(ops.diag(self.total_cm), dtype=self.dtype)
# sum_over_row + sum_over_col =
# 2 * true_positives + false_positives + false_negatives.
denominator = sum_over_row + sum_over_col - true_positives
target_class_ids = ops.convert_to_tensor(
self.target_class_ids, dtype="int32"
)
# Only keep the target classes
true_positives = ops.take_along_axis(
true_positives, target_class_ids, axis=-1
)
denominator = ops.take_along_axis(
denominator, target_class_ids, axis=-1
)
# If the denominator is 0, we need to ignore the class.
num_valid_entries = ops.sum(
ops.cast(ops.greater(denominator, 1e-9), dtype=self.dtype)
)
iou = ops.divide(true_positives, denominator + backend.epsilon())
return ops.divide(
ops.sum(iou, axis=self.axis), num_valid_entries + backend.epsilon()
)
def get_config(self):
config = {
"num_classes": self.num_classes,
"target_class_ids": self.target_class_ids,
"ignore_class": self.ignore_class,
"sparse_y_true": self.sparse_y_true,
"sparse_y_pred": self.sparse_y_pred,
"axis": self.axis,
}
base_config = super().get_config()
return dict(list(base_config.items()) + list(config.items()))
@keras_core_export("keras_core.metrics.BinaryIoU")
class BinaryIoU(IoU):
"""Computes the Intersection-Over-Union metric for class 0 and/or 1.
Formula:
```python
iou = true_positives / (true_positives + false_positives + false_negatives)
```
Intersection-Over-Union is a common evaluation metric for semantic image
segmentation.
To compute IoUs, the predictions are accumulated in a confusion matrix,
weighted by `sample_weight` and the metric is then calculated from it.
If `sample_weight` is `None`, weights default to 1.
Use `sample_weight` of 0 to mask values.
This class can be used to compute IoUs for a binary classification task
where the predictions are provided as logits. First a `threshold` is applied
to the predicted values such that those that are below the `threshold` are
converted to class 0 and those that are above the `threshold` are converted
to class 1.
IoUs for classes 0 and 1 are then computed, the mean of IoUs for the classes
that are specified by `target_class_ids` is returned.
Note: with `threshold=0`, this metric has the same behavior as `IoU`.
Args:
target_class_ids: A tuple or list of target class ids for which the
metric is returned. Options are `[0]`, `[1]`, or `[0, 1]`. With
`[0]` (or `[1]`), the IoU metric for class 0 (or class 1,
respectively) is returned. With `[0, 1]`, the mean of IoUs for the
two classes is returned.
threshold: A threshold that applies to the prediction logits to convert
them to either predicted class 0 if the logit is below `threshold`
or predicted class 1 if the logit is above `threshold`.
name: (Optional) string name of the metric instance.
dtype: (Optional) data type of the metric result.
Examples:
Standalone usage:
>>> m = keras_core.metrics.BinaryIoU(target_class_ids=[0, 1], threshold=0.3)
>>> m.update_state([0, 1, 0, 1], [0.1, 0.2, 0.4, 0.7])
>>> m.result()
0.33333334
>>> m.reset_state()
>>> m.update_state([0, 1, 0, 1], [0.1, 0.2, 0.4, 0.7],
... sample_weight=[0.2, 0.3, 0.4, 0.1])
>>> # cm = [[0.2, 0.4],
>>> # [0.3, 0.1]]
>>> # sum_row = [0.6, 0.4], sum_col = [0.5, 0.5],
>>> # true_positives = [0.2, 0.1]
>>> # iou = [0.222, 0.125]
>>> m.result()
0.17361112
Usage with `compile()` API:
```python
model.compile(
optimizer='sgd',
loss='mse',
metrics=[keras_core.metrics.BinaryIoU(
target_class_ids=[0],
threshold=0.5
)]
)
```
"""
def __init__(
self,
target_class_ids=(0, 1),
threshold=0.5,
name=None,
dtype=None,
):
super().__init__(
num_classes=2,
target_class_ids=target_class_ids,
name=name,
dtype=dtype,
)
self.threshold = threshold
def update_state(self, y_true, y_pred, sample_weight=None):
"""Accumulates the confusion matrix statistics.
Before the confusion matrix is updated, the predicted values are
thresholded to be:
0 for values that are smaller than the `threshold`
1 for values that are larger or equal to the `threshold`
Args:
y_true: The ground truth values.
y_pred: The predicted values.
sample_weight: Optional weighting of each example. Can
be a `Tensor` whose rank is either 0, or the same as `y_true`,
and must be broadcastable to `y_true`. Defaults to `1`.
Returns:
Update op.
"""
y_true = ops.convert_to_tensor(y_true, dtype=self.dtype)
y_pred = ops.convert_to_tensor(y_pred, dtype=self.dtype)
y_pred = ops.cast(y_pred >= self.threshold, self.dtype)
return super().update_state(y_true, y_pred, sample_weight)
def get_config(self):
return {
"target_class_ids": self.target_class_ids,
"threshold": self.threshold,
"name": self.name,
"dtype": self._dtype,
}
@keras_core_export("keras_core.metrics.MeanIoU")
class MeanIoU(IoU):
"""Computes the mean Intersection-Over-Union metric.
Formula:
```python
iou = true_positives / (true_positives + false_positives + false_negatives)
```
Intersection-Over-Union is a common evaluation metric for semantic image
segmentation.
To compute IoUs, the predictions are accumulated in a confusion matrix,
weighted by `sample_weight` and the metric is then calculated from it.
If `sample_weight` is `None`, weights default to 1.
Use `sample_weight` of 0 to mask values.
Note that this class first computes IoUs for all individual classes, then
returns the mean of these values.
Args:
num_classes: The possible number of labels the prediction task can have.
This value must be provided, since a confusion matrix of dimension =
[num_classes, num_classes] will be allocated.
name: (Optional) string name of the metric instance.
dtype: (Optional) data type of the metric result.
ignore_class: Optional integer. The ID of a class to be ignored during
metric computation. This is useful, for example, in segmentation
problems featuring a "void" class (commonly -1 or 255) in
segmentation maps. By default (`ignore_class=None`), all classes are
considered.
sparse_y_true: Whether labels are encoded using integers or
dense floating point vectors. If `False`, the `argmax` function
is used to determine each sample's most likely associated label.
sparse_y_pred: Whether predictions are encoded using integers or
dense floating point vectors. If `False`, the `argmax` function
is used to determine each sample's most likely associated label.
axis: (Optional) The dimension containing the logits. Defaults to `-1`.
Examples:
Standalone usage:
>>> # cm = [[1, 1],
>>> # [1, 1]]
>>> # sum_row = [2, 2], sum_col = [2, 2], true_positives = [1, 1]
>>> # iou = true_positives / (sum_row + sum_col - true_positives))
>>> # result = (1 / (2 + 2 - 1) + 1 / (2 + 2 - 1)) / 2 = 0.33
>>> m = keras_core.metrics.MeanIoU(num_classes=2)
>>> m.update_state([0, 0, 1, 1], [0, 1, 0, 1])
>>> m.result()
0.33333334
>>> m.reset_state()
>>> m.update_state([0, 0, 1, 1], [0, 1, 0, 1],
... sample_weight=[0.3, 0.3, 0.3, 0.1])
>>> m.result().numpy()
0.23809525
Usage with `compile()` API:
```python
model.compile(
optimizer='sgd',
loss='mse',
metrics=[keras_core.metrics.MeanIoU(num_classes=2)])
```
"""
def __init__(
self,
num_classes,
name=None,
dtype=None,
ignore_class=None,
sparse_y_true=True,
sparse_y_pred=True,
axis=-1,
):
target_class_ids = list(range(num_classes))
super().__init__(
name=name,
num_classes=num_classes,
target_class_ids=target_class_ids,
axis=axis,
dtype=dtype,
ignore_class=ignore_class,
sparse_y_true=sparse_y_true,
sparse_y_pred=sparse_y_pred,
)
def get_config(self):
return {
"num_classes": self.num_classes,
"name": self.name,
"dtype": self._dtype,
"ignore_class": self.ignore_class,
"sparse_y_true": self.sparse_y_true,
"sparse_y_pred": self.sparse_y_pred,
"axis": self.axis,
}
@keras_core_export("keras_core.metrics.OneHotIoU")
class OneHotIoU(IoU):
"""Computes the Intersection-Over-Union metric for one-hot encoded labels.
Formula:
```python
iou = true_positives / (true_positives + false_positives + false_negatives)
```
Intersection-Over-Union is a common evaluation metric for semantic image
segmentation.
To compute IoUs, the predictions are accumulated in a confusion matrix,
weighted by `sample_weight` and the metric is then calculated from it.
If `sample_weight` is `None`, weights default to 1.
Use `sample_weight` of 0 to mask values.
This class can be used to compute IoU for multi-class classification tasks
where the labels are one-hot encoded (the last axis should have one
dimension per class). Note that the predictions should also have the same
shape. To compute the IoU, first the labels and predictions are converted
back into integer format by taking the argmax over the class axis. Then the
same computation steps as for the base `IoU` class apply.
Note, if there is only one channel in the labels and predictions, this class
is the same as class `IoU`. In this case, use `IoU` instead.
Also, make sure that `num_classes` is equal to the number of classes in the
data, to avoid a "labels out of bound" error when the confusion matrix is
computed.
Args:
num_classes: The possible number of labels the prediction task can have.
target_class_ids: A tuple or list of target class ids for which the
metric is returned. To compute IoU for a specific class, a list
(or tuple) of a single id value should be provided.
name: (Optional) string name of the metric instance.
dtype: (Optional) data type of the metric result.
ignore_class: Optional integer. The ID of a class to be ignored during
metric computation. This is useful, for example, in segmentation
problems featuring a "void" class (commonly -1 or 255) in
segmentation maps. By default (`ignore_class=None`), all classes are
considered.
sparse_y_pred: Whether predictions are encoded using integers or
dense floating point vectors. If `False`, the `argmax` function
is used to determine each sample's most likely associated label.
axis: (Optional) The dimension containing the logits. Defaults to `-1`.
Examples:
Standalone usage:
>>> y_true = np.array([[0, 0, 1], [1, 0, 0], [0, 1, 0], [1, 0, 0]])
>>> y_pred = np.array([[0.2, 0.3, 0.5], [0.1, 0.2, 0.7], [0.5, 0.3, 0.1],
... [0.1, 0.4, 0.5]])
>>> sample_weight = [0.1, 0.2, 0.3, 0.4]
>>> m = keras_core.metrics.OneHotIoU(num_classes=3, target_class_ids=[0, 2])
>>> m.update_state(
... y_true=y_true, y_pred=y_pred, sample_weight=sample_weight)
>>> # cm = [[0, 0, 0.2+0.4],
>>> # [0.3, 0, 0],
>>> # [0, 0, 0.1]]
>>> # sum_row = [0.3, 0, 0.7], sum_col = [0.6, 0.3, 0.1]
>>> # true_positives = [0, 0, 0.1]
>>> # single_iou = true_positives / (sum_row + sum_col - true_positives))
>>> # mean_iou = (0 / (0.3 + 0.6 - 0) + 0.1 / (0.7 + 0.1 - 0.1)) / 2
>>> m.result()
0.071
Usage with `compile()` API:
```python
model.compile(
optimizer='sgd',
loss='mse',
metrics=[keras_core.metrics.OneHotIoU(
num_classes=3,
target_class_id=[1]
)]
)
```
"""
def __init__(
self,
num_classes,
target_class_ids,
name=None,
dtype=None,
ignore_class=None,
sparse_y_pred=False,
axis=-1,
):
super().__init__(
num_classes=num_classes,
target_class_ids=target_class_ids,
name=name,
dtype=dtype,
ignore_class=ignore_class,
sparse_y_true=False,
sparse_y_pred=sparse_y_pred,
axis=axis,
)
def get_config(self):
return {
"num_classes": self.num_classes,
"target_class_ids": self.target_class_ids,
"name": self.name,
"dtype": self._dtype,
"ignore_class": self.ignore_class,
"sparse_y_pred": self.sparse_y_pred,
"axis": self.axis,
}
@keras_core_export("keras_core.metrics.OneHotMeanIoU")
class OneHotMeanIoU(MeanIoU):
"""Computes mean Intersection-Over-Union metric for one-hot encoded labels.
Formula:
```python
iou = true_positives / (true_positives + false_positives + false_negatives)
```
Intersection-Over-Union is a common evaluation metric for semantic image
segmentation.
To compute IoUs, the predictions are accumulated in a confusion matrix,
weighted by `sample_weight` and the metric is then calculated from it.
If `sample_weight` is `None`, weights default to 1.
Use `sample_weight` of 0 to mask values.
This class can be used to compute the mean IoU for multi-class
classification tasks where the labels are one-hot encoded (the last axis
should have one dimension per class). Note that the predictions should also
have the same shape. To compute the mean IoU, first the labels and
predictions are converted back into integer format by taking the argmax over
the class axis. Then the same computation steps as for the base `MeanIoU`
class apply.
Note, if there is only one channel in the labels and predictions, this class
is the same as class `MeanIoU`. In this case, use `MeanIoU` instead.
Also, make sure that `num_classes` is equal to the number of classes in the
data, to avoid a "labels out of bound" error when the confusion matrix is
computed.
Args:
num_classes: The possible number of labels the prediction task can have.
name: (Optional) string name of the metric instance.
dtype: (Optional) data type of the metric result.
ignore_class: Optional integer. The ID of a class to be ignored during
metric computation. This is useful, for example, in segmentation
problems featuring a "void" class (commonly -1 or 255) in
segmentation maps. By default (`ignore_class=None`), all classes are
considered.
sparse_y_pred: Whether predictions are encoded using natural numbers or
probability distribution vectors. If `False`, the `argmax`
function will be used to determine each sample's most likely
associated label.
axis: (Optional) The dimension containing the logits. Defaults to `-1`.
Examples:
Standalone usage:
>>> y_true = np.array([[0, 0, 1], [1, 0, 0], [0, 1, 0], [1, 0, 0]])
>>> y_pred = np.array([[0.2, 0.3, 0.5], [0.1, 0.2, 0.7], [0.5, 0.3, 0.1],
... [0.1, 0.4, 0.5]])
>>> sample_weight = [0.1, 0.2, 0.3, 0.4]
>>> m = keras_core.metrics.OneHotMeanIoU(num_classes=3)
>>> m.update_state(
... y_true=y_true, y_pred=y_pred, sample_weight=sample_weight)
>>> # cm = [[0, 0, 0.2+0.4],
>>> # [0.3, 0, 0],
>>> # [0, 0, 0.1]]
>>> # sum_row = [0.3, 0, 0.7], sum_col = [0.6, 0.3, 0.1]
>>> # true_positives = [0, 0, 0.1]
>>> # single_iou = true_positives / (sum_row + sum_col - true_positives))
>>> # mean_iou = (0 + 0 + 0.1 / (0.7 + 0.1 - 0.1)) / 3
>>> m.result()
0.048
Usage with `compile()` API:
```python
model.compile(
optimizer='sgd',
loss='mse',
metrics=[keras_core.metrics.OneHotMeanIoU(num_classes=3)])
```
"""
def __init__(
self,
num_classes,
name=None,
dtype=None,
ignore_class=None,
sparse_y_pred=False,
axis=-1,
):
super().__init__(
num_classes=num_classes,
axis=axis,
name=name,
dtype=dtype,
ignore_class=ignore_class,
sparse_y_true=False,
sparse_y_pred=sparse_y_pred,
)
def get_config(self):
return {
"num_classes": self.num_classes,
"name": self.name,
"dtype": self._dtype,
"ignore_class": self.ignore_class,
"sparse_y_pred": self.sparse_y_pred,
"axis": self.axis,
}