def skew(arr, mode="float"):
"""
This function calculates the skew of a given array
Note that the mode must be specified as the automatic mode is float in this case
"""
if len(arr) == 0:
raise ValueError('Empty dataset')
average = bf.average(arr, mode)
answer = (bf.add([(average - i)**2
for i in arr], mode) / len(arr))**(1 / 2)
return answer
def _():
assert bf.average([1, 2, 3, 4, 5, 6]) == 3.5
def _():
assert bf.average([1, 3]) == 2.0
def _():
assert bf.average([1.0]) == 1.0
def _():
assert bf.average([]) == 0.0