Delete list items by condition

Another solution:

res = lst[:1] + [b for a,b in zip(lst, lst[1:]) if a]

print(res)
# [0, 0, 0, 68, 0, 156, 95]

@AndreyNOP suggested a more concise and more elegant version:

res = [b for a,b in zip([1] + lst, lst) if a]

lst = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]
# Поскольку перед первым элементом 
# нет ничего (и нуля в том числе, что соответствует условию), 
# то он добавляется в любом случае.
# К тому-же при i == 0, i - 1 == -1 исключения не будет,
# так-как элемент с индексом -1 присутствует в списке,
# это последний элемент списка 


# Через цикл

new_list = []
for i in range(len(lst)):
    if i == 0 or lst[i - 1] != 0:
        new_list.append(lst[i])
print(new_list)

# Через генератор

print([lst[i] for i in range(len(lst)) if i == 0 or lst[i - 1] != 0])

Because of the crutch with the first element, I didn't want to write an answer, but I was wondering if someone could suggest a more elegant solution

from itertools import tee

def pairwise(iterable):
    a, b = tee(iterable)
    next(b, None)
    return zip(a, b)


lst = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]
new_lst = [j for i, j in pairwise([None] + lst) if i != 0]

Here is another solution, for the collection:

Update - wrapped in try to catch the StopIteration exception

lst = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]
seq = iter(lst)
newlst=[]
try:
    for _ in seq:
        newlst.append(_)
        if _==0:
            next(seq)
except StopIteration:
    pass
print(newlst)

Python has a rich library, but there are not enough methods for processing consecutive pairs from iterable. Probably because there are many variations, and it is not clear how to put them all together. Three examples:

1. Just pairs of [1, 2, 3] -> (1, 2), (2, 3)

2. Cyclic pairs [1, 2, 3] -> (1, 2), (2, 3), (3, 1)

3. Incomplete first pair [1, 2, 3] -> (None, 1), (1, 2), (2, 3)

There is still an incomplete last pair and what else comes to mind.

We need a third option. It is convenient that it works with any iterable, not only with a list:

def pairs(seq):
    prev = None
    for item in seq:
        yield prev, item
        prev = item

lst = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]

print([b for a, b in pairs(lst) if a != 0])

[0, 0, 0, 68, 0, 156, 95]

lst = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]

def cut_after_zero(lst):
    index = 0
    while True:
        try:
            index = lst[:-1].index(0, index)
        except ValueError:
            return lst
        index += 1
        lst.pop(index)

print(cut_after_zero(lst))  # [0, 0, 0, 68, 0, 156, 95]

Without libraries and iterators, with a forgotten loop while True:

lst = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]
zeros = 0
while True:
    try:
        zeros = lst.index(0,zeros)+1
        lst.pop(zeros)
    except:
        break

And also without creating new lists... )) Only the NAV saw that there is a similar solution. But-mine is clearer to me and shorter.

1. you can use filter and map to remove unwanted items from the source list

lst = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]

# поиск индексов нужных элементов
delindex = list(filter(lambda i: lst[i-1]==0, range(1,len(lst)))) # здесь будут индексы удаляемых элементов

# удаление происходит в порядке от большего индекса к меньшему, для этого сортировка списка индексов
delindex.sort(reverse=True)

# удаление элементов
dellist = list(map(lambda d: lst.pop(d), delindex)) # здесь значения удалённых элементов

print(lst) # изменённый исходный список

With the help of the obtained secondary lists, you can restore the original one (if necessary, of course)

1. or generate a new list using filter and map so

lst = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]

newindex = [0]+list(filter(lambda i: lst[i-1]!=0, range(1,len(lst))))
newlist = list(map(lambda n: lst[n], newindex))

print(newlist)

You can remember the sequential number of an item in the list, and work with it. For example like this:

list = [0, 95, 0, 76, 0, 23, 68, 0, 23, 156, 95]
new_list = []

index = 0
for x in list:
    if list[index-1] != 0:
        new_list.append(x)
    index += 1

print(new_list)