tf.sparse.bincount

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Count the number of times an integer value appears in a tensor.

tf.sparse.bincount(
    values, weights=None, axis=0, minlength=None, maxlength=None,
    binary_output=False, name=None
)

This op takes an N-dimensional Tensor, RaggedTensor, or SparseTensor, and returns an N-dimensional int64 SparseTensor where element [i0...i[axis], j] contains the number of times the value j appears in slice [i0...i[axis], :] of the input tensor. Currently, only N=0 and N=-1 are supported.

values A Tensor, RaggedTensor, or SparseTensor whose values should be counted. These tensors must have a rank of 2 if axis=-1.
weights If non-None, must be the same shape as arr. For each value in value, the bin will be incremented by the corresponding weight instead of 1.
axis The axis to slice over. Axes at and below axis will be flattened before bin counting. Currently, only 0, and -1 are supported. If None, all axes will be flattened (identical to passing 0).
minlength If given, ensures the output has length at least minlength, padding with zeros at the end if necessary.
maxlength If given, skips values in values that are equal or greater than maxlength, ensuring that the output has length at most maxlength.
binary_output If True, this op will output 1 instead of the number of times a token appears (equivalent to one_hot + reduce_any instead of one_hot + reduce_add). Defaults to False.
name A name for this op.

A SparseTensor with output.shape = values.shape[:axis] + [N], where N is

  • maxlength (if set);
  • minlength (if set, and minlength > reduce_max(values));
  • 0 (if values is empty);
  • reduce_max(values) + 1 otherwise.

Examples:

Bin-counting every item in individual batches

This example takes an input (which could be a Tensor, RaggedTensor, or SparseTensor) and returns a SparseTensor where the value of (i,j) is the number of times value j appears in batch i.

data = np.array([[10, 20, 30, 20], [11, 101, 11, 10001]], dtype=np.int64)
output = tf.sparse.bincount(data, axis=-1)
print(output)
SparseTensor(indices=tf.Tensor(
[[    0    10]
 [    0    20]
 [    0    30]
 [    1    11]
 [    1   101]
 [    1 10001]], shape=(6, 2), dtype=int64),
 values=tf.Tensor([1 2 1 2 1 1], shape=(6,), dtype=int64),
 dense_shape=tf.Tensor([    2 10002], shape=(2,), dtype=int64))

Bin-counting with defined output shape

This example takes an input (which could be a Tensor, RaggedTensor, or SparseTensor) and returns a SparseTensor where the value of (i,j) is the number of times value j appears in batch i. However, all values of j above 'maxlength' are ignored. The dense_shape of the output sparse tensor is set to 'minlength'. Note that, while the input is identical to the example above, the value '10001' in batch item 2 is dropped, and the dense shape is [2, 500] instead of [2,10002] or [2, 102].

minlength = maxlength = 500
data = np.array([[10, 20, 30, 20], [11, 101, 11, 10001]], dtype=np.int64)
output = tf.sparse.bincount(
   data, axis=-1, minlength=minlength, maxlength=maxlength)
print(output)
SparseTensor(indices=tf.Tensor(
[[  0  10]
 [  0  20]
 [  0  30]
 [  1  11]
 [  1 101]], shape=(5, 2), dtype=int64),
 values=tf.Tensor([1 2 1 2 1], shape=(5,), dtype=int64),
 dense_shape=tf.Tensor([  2 500], shape=(2,), dtype=int64))

Binary bin-counting

This example takes an input (which could be a Tensor, RaggedTensor, or SparseTensor) and returns a SparseTensor where (i,j) is 1 if the value j appears in batch i at least once and is 0 otherwise. Note that, even though some values (like 20 in batch 1 and 11 in batch 2) appear more than once, the 'values' tensor is all 1s.

data = np.array([[10, 20, 30, 20], [11, 101, 11, 10001]], dtype=np.int64)
output = tf.sparse.bincount(data, binary_output=True, axis=-1)
print(output)
SparseTensor(indices=tf.Tensor(
[[    0    10]
 [    0    20]
 [    0    30]
 [    1    11]
 [    1   101]
 [    1 10001]], shape=(6, 2), dtype=int64),
 values=tf.Tensor([1 1 1 1 1 1], shape=(6,), dtype=int64),
 dense_shape=tf.Tensor([    2 10002], shape=(2,), dtype=int64))

Weighted bin-counting

This example takes two inputs - a values tensor and a weights tensor. These tensors must be identically shaped, and have the same row splits or indices in the case of RaggedTensors or SparseTensors. When performing a weighted count, the op will output a SparseTensor where the value of (i, j) is the sum of the values in the weight tensor's batch i in the locations where the values tensor has the value j. In this case, the output dtype is the same as the dtype of the weights tensor.

data = np.array([[10, 20, 30, 20], [11, 101, 11, 10001]], dtype=np.int64)
weights = [[2, 0.25, 15, 0.5], [2, 17, 3, 0.9]]
output = tf.sparse.bincount(data, weights=weights, axis=-1)
print(output)
SparseTensor(indices=tf.Tensor(
[[    0    10]
 [    0    20]
 [    0    30]
 [    1    11]
 [    1   101]
 [    1 10001]], shape=(6, 2), dtype=int64),
 values=tf.Tensor([2. 0.75 15. 5. 17. 0.9], shape=(6,), dtype=float32),
 dense_shape=tf.Tensor([    2 10002], shape=(2,), dtype=int64))