jax.numpy.transpose

jax.numpy.transpose(a, axes=None)

Return a transposed version of an N-dimensional array.

JAX implementation of numpy.transpose(), implemented in terms of jax.lax.transpose().

Parameters:

• a (ArrayLike) – input array

• axes (Sequence[int] | None) – optionally specify the permutation using a length-a.ndim sequence of integers i satisfying 0 <= i < a.ndim. Defaults to range(a.ndim)[::-1], i.e. reverses the order of all axes.

Returns:

transposed copy of the array.

Return type:

Array

See also

• jax.Array.transpose(): equivalent function via an Array method.

• jax.Array.T: equivalent function via an Array property.

• jax.numpy.matrix_transpose(): transpose the last two axes of an array. This is suitable for working with batched 2D matrices.

• jax.numpy.swapaxes(): swap any two axes in an array.

• jax.numpy.moveaxis(): move an axis to another position in the array.

Note

Unlike numpy.transpose(), jax.numpy.transpose() will return a copy rather than a view of the input array. However, under JIT, the compiler will optimize-away such copies when possible, so this doesn’t have performance impacts in practice.

Examples

For a 1D array, the transpose is the identity:

>>> x = jnp.array([1, 2, 3, 4])
>>> jnp.transpose(x)
Array([1, 2, 3, 4], dtype=int32)

For a 2D array, the transpose is a matrix transpose:

>>> x = jnp.array([[1, 2],
...                [3, 4]])
>>> jnp.transpose(x)
Array([[1, 3],
       [2, 4]], dtype=int32)

For an N-dimensional array, the transpose reverses the order of the axes:

>>> x = jnp.zeros(shape=(3, 4, 5))
>>> jnp.transpose(x).shape
(5, 4, 3)

The axes argument can be specified to change this default behavior:

>>> jnp.transpose(x, (0, 2, 1)).shape
(3, 5, 4)

Since swapping the last two axes is a common operation, it can be done via its own API, jax.numpy.matrix_transpose():

>>> jnp.matrix_transpose(x).shape
(3, 5, 4)

For convenience, transposes may also be performed using the jax.Array.transpose() method or the jax.Array.T property:

>>> x = jnp.array([[1, 2],
...                [3, 4]])
>>> x.transpose()
Array([[1, 3],
       [2, 4]], dtype=int32)
>>> x.T
Array([[1, 3],
       [2, 4]], dtype=int32)