How do I replace elements in a list over a certain threshold with the previous element in that list?

Question

I have a multiple numpy lists with thousands of data points each. There are spikes that are due to hardware issues that I wish to remove. My plan is to replace every spike with the previous element of the array to maintain consistency.

Answer 1

I tried to make the solution far too complicated. The easiest way is as follows;

for x in clockList:
    if x > 2000000000:
        clockList[count] = clockList[count - 1]
        count += 1
    else:
        count += 1