I need to calculate the **cosine similarity** between **two lists**, let's say for example list 1 which is dataSetI and list 2 which is dataSetII. I cannot use anything such as *numpy* or a statistics module. I must use common modules (math, etc) (and the least modules as possible, at that, to reduce time spent).

Let's say dataSetI is [3, 45, 7, 2] and dataSetII is [2, 54, 13, 15]. The length of the lists are *always* equal.

Of course, the cosine similarity is between *0 and 1*, and for the sake of it, it will be rounded to the third or fourth decimal with format(round(cosine, 3)).

Thank you very much in advance for helping.