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A transformation that groups elements and performs a reduction.
tf.data.experimental.group_by_reducer(
key_func, reducer
)
This transformation maps element of a dataset to a key using key_func
and
groups the elements by key. The reducer
is used to process each group; its
init_func
is used to initialize state for each group when it is created, the
reduce_func
is used to update the state every time an element is mapped to
the matching group, and the finalize_func
is used to map the final state to
an output value.
key_func
: A function mapping a nested structure of tensors
(having shapes and types defined by self.output_shapes
and
self.output_types
) to a scalar tf.int64
tensor.reducer
: An instance of Reducer
, which captures the reduction logic using
the init_func
, reduce_func
, and finalize_func
functions.A Dataset
transformation function, which can be passed to
tf.data.Dataset.apply
.