Function identity

numpy/_core/numeric.py:2179–2215

Return the identity array. The identity array is a square array with ones on the main diagonal. Parameters ---------- n : int Number of rows (and columns) in `n` x `n` output. dtype : data-type, optional Data-type of the output. Defaults to ``float``.

(n, dtype=None, *, like=None)

@finalize_array_function_like
@set_module('numpy')
def identity(n, dtype=None, *, like=None):
    """
    Return the identity array.

    The identity array is a square array with ones on
    the main diagonal.

    Parameters
    ----------
    n : int
        Number of rows (and columns) in `n` x `n` output.
    dtype : data-type, optional
        Data-type of the output.  Defaults to ``float``.
    ${ARRAY_FUNCTION_LIKE}

        .. versionadded:: 1.20.0

    Returns
    -------
    out : ndarray
        `n` x `n` array with its main diagonal set to one,
        and all other elements 0.

    Examples
    --------
    >>> import numpy as np
    >>> np.identity(3)
    array([[1.,  0.,  0.],
           [0.,  1.,  0.],
           [0.,  0.,  1.]])

    """
    if like is not None:
        return _identity_with_like(like, n, dtype=dtype)

    from numpy import eye
    return eye(n, dtype=dtype, like=like)


_identity_with_like = array_function_dispatch()(identity)