I want to create a list comprehension that keeps the previous value unless the next value is higher.
Example:
list_input = [3, 4, 2, 8, 9, 3, 3, 4, 20, 1]
list_output = [3, 4, 4, 8, 9, 9, 9, 9, 20, 20]
Is there a way to do this in a single list comprehension expression?
One way to really just do it in a list comprehension:
list_output = [m for m in list_input[:1] for x in list_input for m in [max(m, x)]] Better way:
from itertools import accumulate list_output = list(accumulate(list_input, max)) Requested explanation for the list comprehension: It does pretty much the same as this:
list_output = [] if list_input: m = list_input[0] for x in list_input: m = max(m, x) list_output.append(m) 
