Python - Closeness of two values on a logarithmic scale
So the solution I have is : 
linear_closeness = 1 - (difference / max_deviation) 
exponential_closeness = 10^linear_closeness / 10 
This is suitable for me. I am open to better solutions.
I have two, time value series (using pandas) and would like to represent the "closeness" of the last value in each series in regards to each other on a logarithmic scale between 0 and 1. 0 being very far away and 1 being the same.
I am not sure how to approach this and any help would be appreciated.