tf.strided_slice

tf.strided_slice

tf.strided_slice

strided_slice(
    input_,
    begin,
    end,
    strides=None,
    begin_mask=0,
    end_mask=0,
    ellipsis_mask=0,
    new_axis_mask=0,
    shrink_axis_mask=0,
    var=None,
    name=None
)

Defined in tensorflow/python/ops/array_ops.py.

See the guide: Tensor Transformations > Slicing and Joining

Extracts a strided slice of a tensor (generalized python array indexing).

Most users will want to use tf.Tensor.__getitem__ and tf.Variable.__getitem__. That allows NumPy style slicing syntax (i.e. tensor[..., 3:4:-1, tf.newaxis, 3]). This op is the low-level interface that are used to implement operators. Those interfaces are much more friendly, and highly recommended.

To a first order, this operation extracts a slice of size end - begin from a tensor input starting at the location specified by begin. The slice continues by adding stride to the begin index until all dimensions are not less than end. Note that components of stride can be negative, which causes a reverse slice.

This operation can be thought of an encoding of a numpy style sliced range. Given a python slice input[, , ..., ] this function will be called as follows.

begin, end, and strides will be all length n. n is in general not the same dimensionality as input.

For the ith spec, begin_mask, end_mask, ellipsis_mask, new_axis_mask, and shrink_axis_mask will have the ith bit corresponding to the ith spec.

If the ith bit of begin_mask is non-zero, begin[i] is ignored and the fullest possible range in that dimension is used instead. end_mask works analogously, except with the end range.

foo[5:,:,:3] on a 7x8x9 tensor is equivalent to foo[5:7,0:8,0:3]. foo[::-1] reverses a tensor with shape 8.

If the ith bit of ellipsis_mask is non-zero, as many unspecified dimensions as needed will be inserted between other dimensions. Only one non-zero bit is allowed in ellipsis_mask.

For example foo[3:5,...,4:5] on a shape 10x3x3x10 tensor is equivalent to foo[3:5,:,:,4:5] and foo[3:5,...] is equivalent to foo[3:5,:,:,:].

If the ith bit of new_axis_mask is one, then begin, end, and stride are ignored and a new length 1 dimension is added at this point in the output tensor.

For example foo[3:5,4] on a 10x8 tensor produces a shape 2 tensor whereas foo[3:5,4:5] produces a shape 2x1 tensor with shrink_mask being 1<<1 == 2.

If the ith bit of shrink_axis_mask is one, then begin, end[i], and stride[i] are used to do a slice in the appropriate dimension, but the output tensor will be reduced in dimensionality by one. This is only valid if the ith entry of slice[i]==1.

NOTE: begin and end are zero-indexed.strides` entries must be non-zero.

# 'input' is [[[1, 1, 1], [2, 2, 2]],
#             [[3, 3, 3], [4, 4, 4]],
#             [[5, 5, 5], [6, 6, 6]]]
tf.strided_slice(input, [1, 0, 0], [2, 1, 3], [1, 1, 1]) ==> [[[3, 3, 3]]]
tf.strided_slice(input, [1, 0, 0], [2, 2, 3], [1, 1, 1]) ==> [[[3, 3, 3],
                                                               [4, 4, 4]]]
tf.strided_slice(input, [1, -1, 0], [2, -3, 3], [1, -1, 1]) ==>[[[4, 4, 4],
                                                                 [3, 3, 3]]]

Args:

• input_: A Tensor.
• begin: An int32 or int64 Tensor.
• end: An int32 or int64 Tensor.
• strides: An int32 or int64 Tensor.
• begin_mask: An int32 mask.
• end_mask: An int32 mask.
• ellipsis_mask: An int32 mask.
• new_axis_mask: An int32 mask.
• shrink_axis_mask: An int32 mask.
• var: The variable corresponding to input_ or None
• name: A name for the operation (optional).

Returns:

A Tensor the same type as input.