Replacing List Items

There is a list of integers. Replace negative by -1, positive - by number 1, keep zero unchanged.

1st option - filling a new list depending on the values of the first one:

listOrigin = [10, -15, 3, 8, 0, 9, -6, 13, -1, 5]
listMask = []
for item in listOrigin:
    if item > 0:
        listMask.append(1)
    elif item < 0:
        listMask.append(-1)
    else:
        listMask.append(0)

print(listOrigin)
print(listMask)

With comments:

# the old list
listOrigin = [10, -15, 3, 8, 0, 9, -6, 13, -1, 5]

# the new list
listMask = []

# enumeration of the elements of the old list
for item in listOrigin:
    if item > 0: # If the element is greater than 0,
        listMask.append(1) # 1 is added to the new list.
    elif item < 0: # If the element is less than 0,
        listMask.append(-1) # -1 is added to the list.
    else: # If the element is 0,
        listMask.append(0) # 0 is added to the list.

# output of source and derived lists
print(listOrigin)
print(listMask)

2nd option - replacing items directly in the source list:

listOne = [10, -15, 3, 8, 0, 9, -6, 13, -1, 5]
print(listOne)

for i in range(len(listOne)):
    if listOne[i] > 0:
        listOne[i] = 1
    elif listOne[i] < 0:
        listOne[i] = -1

print(listOne)

With comments:

listOne = [10, -15, 3, 8, 0, 9, -6, 13, -1, 5]
print(listOne) # the list in its original form

# The i value changes from 0 to
# the index of the last item in the list,
# which is equal to the length of the list minus 1.
for i in range(len(listOne)):
    if listOne[i] > 0: # If an element with index i is greater than 0,
        listOne[i] = 1 # then it is replaced by 1.
    elif listOne[i] < 0: # If an element with index i is less than 0,
        listOne[i] = -1 # then it is replaced by -1.
    # In all other cases (the item is 0)
        # the element will remain as it is.

print(listOne) # output of the changed list

The result of an execution of scripts:

[10, -15, 3, 8, 0, 9, -6, 13, -1, 5]
[1, -1, 1, 1, 0, 1, -1, 1, -1, 1]