"""
Utility functions for probing / sampling.
"""


def extract_samples(items, n=5):
    """
    Extract up to n sample elements from the the given dict or list.

    If *items* is a dict return the elements from the list of keys.
    """
    l = len(items)
    if l <= n:
        return items
    poss = []
    step = (l + 1) / n
    for i in range(n):
        pos = int(step * i)
        if pos < l and (not poss or pos > poss[-1]):
            poss.append(pos)
    items_list = list(items)
    return [items_list[pos] for pos in poss]