Change Value in a list based on previous condition

Question

I have a list of zeros and ones. I am trying to replace the a value of 1 with a 0 if the previous value is also a 1 for a desired output as shown below.

list =     [1,1,1,0,0,0,1,0,1,1,0]
new_list = [1,0,0,0,0,0,1,0,1,0,0]

I've tried using a for loop to no avail. Any suggestions?

Answer 1

How about this for loop:

list =     [1,1,1,0,0,0,1,0,1,1,0]
new_list = []

ant=0
for i in list:
    if ant ==0 and i==1:
        new_list.append(1)
    else:
        new_list.append(0)
    ant=i

Answer 2

question_list = [1,1,1,0,0,0,1,0,1,1,0]
new_list = [question_list[0]] # notice we put the first element here
for i in range(1, len(question_list) + 1):
    # check if the current and previous element are 1
    if question_list[i] == 1 and question_list[i - 1] == 1:
        new_list.append(0)
    else:
        new_list.append(question_list[i])

The idea here is we iterate over the list, while checking the previous element.