Moving average

A sensor sends one number each second. To smooth the numbers, you want the average of every group of size neighbouring numbers.

Write moving_average(values, size). It returns a list. The first item is the average of the first size numbers. The second item is the average of the numbers from position 1 to position size. And so on.

• The result has len(values) - size + 1 items.
• If size is less than 1, or larger than the number of values, raise a ValueError.
• Averages can have decimals. The tests accept a small rounding difference (0.0001).

Examples

Call	Result
moving_average([1, 2, 3, 4, 5], 2)	[1.5, 2.5, 3.5, 4.5]
moving_average([10, 20, 30], 3)	[20]
moving_average([1, 2, 3], 0)	raises an error