qiskit/tools/qi/qi.py
def shannon_entropy(pvec, base=2):
    """
    Compute the Shannon entropy of a probability vector.

    The shannon entropy of a probability vector pv is defined as
    $H(pv) = - \\sum_j pv[j] log_b (pv[j])$ where $0 log_b 0 = 0$.

    Args:
        pvec (array_like): a probability vector.
        base (int): the base of the logarith

    Returns:
        float: The Shannon entropy H(pvec).
    """
    # pylint: disable=missing-docstring
    if base == 2:
        def logfn(x):
            return - x * np.log2(x)
    elif base == np.e:
        def logfn(x):
            return - x * np.log(x)
    else:
        def logfn(x):
            return -x * np.log(x) / np.log(base)

    h = 0.
    for x in pvec:
        if 0 < x < 1:
            h += logfn(x)
    return h
def shannon_entropy(pvec, base=2):
    """
    Compute the Shannon entropy of a probability vector.

    The shannon entropy of a probability vector pv is defined as
    $H(pv) = - \\sum_j pv[j] log_b (pv[j])$ where $0 log_b 0 = 0$.

    Args:
        pvec (array_like): a probability vector.
        base (int): the base of the logarith

    Returns:
        float: The Shannon entropy H(pvec).
    """
    # pylint: disable=missing-docstring
    if base == 2:
        def logfn(x):
            return - x * np.log2(x)
    elif base == np.e:
        def logfn(x):
            return - x * np.log(x)
    else:
        def logfn(x):
            return -x * np.log(x) / np.log(base)

    h = 0.
    for x in pvec:
        if 0 < x < 1:
            h += logfn(x)
    return h
Compute the Shannon entropy of a probability vector.

    The shannon entropy of a probability vector pv is defined as
    $H(pv) = - \\sum_j pv[j] log_b (pv[j])$ where $0 log_b 0 = 0$.

    Args:
        pvec (array_like): a probability vector.
        base (int): the base of the logarith

    Returns:
        float: The Shannon entropy H(pvec).