jax.numpy.unique#

jax.numpy.unique(ar, return_index=False, return_inverse=False, return_counts=False, axis=None, *, size=None, fill_value=None)[source]#

Find the unique elements of an array.

LAX-backend implementation of numpy.unique().

Because the size of the output of unique is data-dependent, the function is not typically compatible with JIT. The JAX version adds the optional size argument which must be specified statically for jnp.unique to be used within some of JAX’s transformations.

Original docstring below.

Returns the sorted unique elements of an array. There are three optional outputs in addition to the unique elements:

  • the indices of the input array that give the unique values

  • the indices of the unique array that reconstruct the input array

  • the number of times each unique value comes up in the input array

Parameters:

  • ar (array_like) – Input array. Unless axis is specified, this will be flattened if it is not already 1-D.

  • return_index (bool, optional) – If True, also return the indices of ar (along the specified axis, if provided, or in the flattened array) that result in the unique array.

  • return_inverse (bool, optional) – If True, also return the indices of the unique array (for the specified axis, if provided) that can be used to reconstruct ar.

  • return_counts (bool, optional) – If True, also return the number of times each unique item appears in ar.

  • size (int, optional) – If specified, the first size unique elements will be returned. If there are fewer unique elements than size indicates, the return value will be padded with fill_value.

  • fill_value (array_like, optional) – When size is specified and there are fewer than the indicated number of elements, the remaining elements will be filled with fill_value. The default is the minimum value along the specified axis of the input.

  • axis (Optional[int]) –

Returns:

  • unique (ndarray) – The sorted unique values.

  • unique_indices (ndarray, optional) – The indices of the first occurrences of the unique values in the original array. Only provided if return_index is True.

  • unique_inverse (ndarray, optional) – The indices to reconstruct the original array from the unique array. Only provided if return_inverse is True.

  • unique_counts (ndarray, optional) – The number of times each of the unique values comes up in the original array. Only provided if return_counts is True.

    New in version 1.9.0.