dataset_group_by_window: Group windows of elements by key and reduce them

In tfdatasets: Interface to 'TensorFlow' Datasets

Group windows of elements by key and reduce them

Description

Group windows of elements by key and reduce them

Usage

dataset_group_by_window(
  dataset,
  key_func,
  reduce_func,
  window_size = NULL,
  window_size_func = NULL,
  name = NULL
)

Arguments

dataset	a TF Dataset
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.
reduce_func	A function mapping a key and a dataset of up to window_size consecutive elements matching that key to another dataset.
window_size	A tf.int64 scalar tf.Tensor, representing the number of consecutive elements matching the same key to combine in a single batch, which will be passed to reduce_func. Mutually exclusive with window_size_func.
window_size_func	A function mapping a key to a tf.int64 scalar tf.Tensor, representing the number of consecutive elements matching the same key to combine in a single batch, which will be passed to reduce_func. Mutually exclusive with window_size.
name	(Optional.) A name for the Tensorflow operation.

Details

This transformation maps each consecutive element in a dataset to a key using key_func() and groups the elements by key. It then applies reduce_func() to at most window_size_func(key) elements matching the same key. All except the final window for each key will contain window_size_func(key) elements; the final window may be smaller.

You may provide either a constant window_size or a window size determined by the key through window_size_func.

window_size <-  5
dataset <- range_dataset(to = 10) %>%
  dataset_group_by_window(
    key_func = function(x) x %% 2,
    reduce_func = function(key, ds) dataset_batch(ds, window_size),
    window_size = window_size
  )

it <- as_array_iterator(dataset)
while (!is.null(elem <- iter_next(it)))
  print(elem)
#> tf.Tensor([0 2 4 6 8], shape=(5), dtype=int64)
#> tf.Tensor([1 3 5 7 9], shape=(5), dtype=int64)

See Also

• https://www.tensorflow.org/api_docs/python/tf/data/Dataset#group_by_window

tfdatasets documentation built on June 30, 2022, 1:04 a.m.