def idle_cpu_count(mincpu=1):
    """Estimate number of idle CPUs, for use by multiprocessing code
    needing to determine how many processes can be run without excessive
    load. This function uses :func:`os.getloadavg` which is only available
    under a Unix OS.

    Parameters
    ----------
    mincpu : int
      Minimum number of CPUs to report, independent of actual estimate

    Returns
    -------
    idle : int
      Estimate of number of idle CPUs
    """

    if PY2:
        ncpu = mp.cpu_count()
    else:
        ncpu = os.cpu_count()
    idle = int(ncpu - np.floor(os.getloadavg()[0]))
    return max(mincpu, idle)