Fastest way to zero out low values in array?

Question

So, lets say I have 100,000 float arrays with 100 elements each. I need the highest X number of values, BUT only if they are greater than Y. Any element not matching this

Answer 1

Using numpy:

# assign zero to all elements less than or equal to `lowValY`
a[a<=lowValY] = 0 
# find n-th largest element in the array (where n=highCountX)
x = partial_sort(a, highCountX, reverse=True)[:highCountX][-1]
# 
a[a

Where partial_sort could be:

def partial_sort(a, n, reverse=False):
    #NOTE: in general it should return full list but in your case this will do
    return sorted(a, reverse=reverse)[:n] 

The expression a[a can be written without numpy as follows:

for i, x in enumerate(a):
    if x < value:
       a[i] = 0