tf.keras.Metric

Encapsulates metric logic and state.

tf.keras.Metric(
    dtype=None, name=None
)

name (Optional) string name of the metric instance.
dtype (Optional) data type of the metric result.

Example:

m = SomeMetric(...)
for input in ...:
    m.update_state(input)
print('Final result: ', m.result())

Usage with compile() API:

model = keras.Sequential()
model.add(keras.layers.Dense(64, activation='relu'))
model.add(keras.layers.Dense(64, activation='relu'))
model.add(keras.layers.Dense(10, activation='softmax'))

model.compile(optimizer=keras.optimizers.RMSprop(0.01),
              loss=keras.losses.CategoricalCrossentropy(),
              metrics=[keras.metrics.CategoricalAccuracy()])

data = np.random.random((1000, 32))
labels = np.random.random((1000, 10))

model.fit(data, labels, epochs=10)

To be implemented by subclasses:

  • __init__(): All state variables should be created in this method by calling self.add_variable() like: self.var = self.add_variable(...)
  • update_state(): Has all updates to the state variables like: self.var.assign(...).
  • result(): Computes and returns a scalar value or a dict of scalar values for the metric from the state variables.

Example subclass implementation:

class BinaryTruePositives(Metric):

    def __init__(self, name='binary_true_positives', **kwargs):
        super().__init__(name=name, **kwargs)
        self.true_positives = self.add_variable(
            shape=(),
            initializer='zeros',
            name='true_positives'
        )

    def update_state(self, y_true, y_pred, sample_weight=None):
        y_true = ops.cast(y_true, "bool")
        y_pred = ops.cast(y_pred, "bool")

        values = ops.logical_and(
            ops.equal(y_true, True), ops.equal(y_pred, True))
        values = ops.cast(values, self.dtype)
        if sample_weight is not None:
            sample_weight = ops.cast(sample_weight, self.dtype)
            sample_weight = ops.broadcast_to(
                sample_weight, ops.shape(values)
            )
            values = ops.multiply(values, sample_weight)
        self.true_positives.assign(self.true_positives + ops.sum(values))

    def result(self):
        return self.true_positives

dtype

variables

Methods

add_variable

View source

add_variable(
    shape, initializer, dtype=None, aggregation='sum', name=None
)

add_weight

View source

add_weight(
    shape=(), initializer=None, dtype=None, name=None
)

from_config

View source

@classmethod
from_config(
    config
)

get_config

View source

get_config()

Return the serializable config of the metric.

reset_state

View source

reset_state()

Reset all of the metric state variables.

This function is called between epochs/steps, when a metric is evaluated during training.

result

View source

result()

Compute the current metric value.

Returns
A scalar tensor, or a dictionary of scalar tensors.

stateless_reset_state

View source

stateless_reset_state()

stateless_result

View source

stateless_result(
    metric_variables
)

stateless_update_state

View source

stateless_update_state(
    metric_variables, *args, **kwargs
)

update_state

View source

update_state(
    *args, **kwargs
)

Accumulate statistics for the metric.

__call__

View source

__call__(
    *args, **kwargs
)

Call self as a function.