Replacing items in a list with items from another list in python-CodePudding

list1 = [3,4,1,1,0,3,1,0,4,3,3,2,3]

list2 = [0,2,1,0,5]

Would it be possible to replace each 3 in list1 with a 0 from list2? If so, how would I go about doing this?

CodePudding user response：

You could create an iterator for list2, and then call next() to replace the next element in list1 that is equal to 3, while using a list comprehension.

list1 = [3,4,1,1,0,3,1,0,4,3,3,2,3]
list2 = [0,2,1,0,5]
l2 = iter(list2)

out = [i if i!=3 else next(l2) for i in list1]
print(out)

Output:

[0, 4, 1, 1, 0, 2, 1, 0, 4, 1, 0, 2, 5]

CodePudding user response：

We can use two pointers to keep track of list1 and list2. Then we replace each 3 in list1 with a value from list2 even it is not 0 until traversing to the end of any of the list.

list1 = [3, 4, 1, 1, 0, 3, 1, 0, 4, 3, 3, 2, 3]
list2 = [0, 0, 0, 0, 0]
x = 0
y = 0
while x < len(list1) and y < len(list2):
    if list1[x] == 3:
        list1[x] = list2[y]
        y  = 1
    x  = 1
print(list1)

Output:

[0, 4, 1, 1, 0, 0, 1, 0, 4, 0, 0, 2, 0]

CodePudding user response：

list1 = [3,4,1,1,0,3,1,0,4,3,3,2,3]
list2 = [0,2,1,0,5]
l1_num = 3 # number to be replaced in list 1
l2_num = 0 # number to be replaced in list 2
n = min(list1.count(l1_num),list2.count(l2_num))
for i in range(n):
    list1[list1.index(l1_num)] = l2_num
    list2[list2.index(l2_num)] = l1_num
#list1 = [0, 4, 1, 1, 0, 0, 1, 0, 4, 3, 3, 2, 3]
#list2 = [3, 2, 1, 3, 5]

CodePudding user response：

we can use for in and store our needed short list value out of the loop. like the following code will replace all 3 in list1 with zeros and all 0 in list2 with 3s in list1:

    list1 = [3,4,1,1,0,3,1,0,4,3,3,2,3]
    list2 = [0,1,0,3,0]
    #shortlistval will be used to store short list desired value
    shortlistVal =1;#default val is just for declaration 
    for i1 in range(0, len(list1)):
        for i in range(0,len(list2)):
            if list1[i1] ==3 and list2[i] == 0:
                shortlistVal=list2[i]
                list2[i]=list1[i1]
        if list1[i1]==3:
            list1[i1]= shortlistVal
    print(list1)
    print(list2)

Output:

   [0, 4, 1, 1, 0, 0, 1, 0, 4, 0, 0, 2, 0]
   [3, 1, 3, 3, 3]

CodePudding user response：

Use two for loops and replace each 3 for 0 s in list 2.

list1 = [3,4,1,1,0,3,1,0,4,3,3,2,3]
list2 = [0,2,1,0,5]

for i in range(list2.count(0)):
    for x in list1:
        if x == 3: list1[list1.index(x)] = 0; break

print(list1)

output:

[0, 4, 1, 1, 0, 0, 1, 0, 4, 3, 3, 2, 3]