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tf.gather

Gather slices from params axis axis according to indices.

tf.gather(
    params, indices, validate_indices=None, axis=None, batch_dims=0, name=None
)

Gather slices from params axis axis according to indices. indices must be an integer tensor of any dimension (usually 0-D or 1-D).

For 0-D (scalar) indices:

$$\begin{align*} output[p_0, ..., p_{axis-1}, && &&& p_{axis + 1}, ..., p_{N-1}] = \\ params[p_0, ..., p_{axis-1}, && indices, &&& p_{axis + 1}, ..., p_{N-1}] \end{align*}$$

Where N = ndims(params).

For 1-D (vector) indices with batch_dims=0:

$$\begin{align*} output[p_0, ..., p_{axis-1}, && &i, &&p_{axis + 1}, ..., p_{N-1}] =\\ params[p_0, ..., p_{axis-1}, && indices[&i], &&p_{axis + 1}, ..., p_{N-1}] \end{align*}$$

In the general case, produces an output tensor where:

$$\begin{align*} output[p_0, &..., p_{axis-1}, & &i_{B}, ..., i_{M-1}, & p_{axis + 1}, &..., p_{N-1}] = \\ params[p_0, &..., p_{axis-1}, & indices[p_0, ..., p_{B-1}, &i_{B}, ..., i_{M-1}], & p_{axis + 1}, &..., p_{N-1}] \end{align*}$$

Where N = ndims(params), M = ndims(indices), and B = batch_dims. Note that params.shape[:batch_dims] must be identical to indices.shape[:batch_dims].

The shape of the output tensor is:

output.shape = params.shape[:axis] + indices.shape[batch_dims:] + params.shape[axis + 1:].

Note that on CPU, if an out of bound index is found, an error is returned. On GPU, if an out of bound index is found, a 0 is stored in the corresponding output value.

See also tf.gather_nd.

Args
`params`	The `Tensor` from which to gather values. Must be at least rank `axis + 1`.
`indices`	The index `Tensor`. Must be one of the following types: `int32`, `int64`. Must be in range `[0, params.shape[axis])`.
`validate_indices`	Deprecated, does nothing.
`axis`	A `Tensor`. Must be one of the following types: `int32`, `int64`. The `axis` in `params` to gather `indices` from. Must be greater than or equal to `batch_dims`. Defaults to the first non-batch dimension. Supports negative indexes.
`batch_dims`	An `integer`. The number of batch dimensions. Must be less than or equal to `rank(indices)`.
`name`	A name for the operation (optional).

Returns
A `Tensor`. Has the same type as `params`.

© 2020 The TensorFlow Authors. All rights reserved.
Licensed under the Creative Commons Attribution License 3.0.
Code samples licensed under the Apache 2.0 License.
https://www.tensorflow.org/versions/r2.4/api_docs/python/tf/gather